Game Start
You'll typically start at your Void buff (the purple area near your tower). Clear and take the buff before heading to lane.
Early Game
By the time you reach the minions, they will already be fighting each other. Clearing this first wave is a race between you and the enemy, as whoever clears first will automatically gain pressure, which can be used to poke the enemy. Taking early damage can put people on the defensive and can mentally be the first step in dictating who will dominate the laning phase. It also can force the early use of potions, leading to an earlier first-back, which means even more pressure and a lead in farming XP and gold.
If you find yourself out-pressured, back off without taking too much poke while concentrating on clearing the wave. If you manage to outclear your opponent try to get some poke in on the enemy gods.
Xbalanque has one of the worst clears amongst ADCs in the early game, and you will find yourself losing wave pressure in most matchups. You'll typically find yourself forced back, near or under your tower in the first few minutes. However, he can provide a small amount of trade, as 
Branching Bolas will hit enemy gods that are near the wave. At level 1 and 2 of Branching Bola (until level 6), you can keep the ability toggled on the entire time as the mana loss is negligible.
After 3 minions die from the second wave, you and your Support should reach level 2. The goal is usually to clear these 3 minions before your opponent does, as gaining your second ability before the enemy can allow for even more pressure. Keep an eye on the positioning of both Supports and the minions' health bars as they will dictate if and how a level 2 fight will happen:
- Winning: you and your support hit lvl 2 first
- Even: both teams hit level 2 at the same time
- Losing: enemies hit level 2 first
You want to know your matchups and which abilities will be gained by your Support and the enemy ADC / Support. Some level 2 abilities won't be a large threat, while others (e.g.
Sobek's
Charge Prey or
Ymir's
Frost Breath) have stun/root/displacement actions that can put the other Duo under immense pressure and lead to an early kill.
In a situation where you win or go even in the level 2 race, and your abilities provide high pressure, you may plan to be aggressive. In this case, your Support will usually be positioned closer to the enemy, behind or next to your front melee minions. If you plan to be aggressive, the moment lvl 2 is reached, your Support will try to go in on the most vulnerable enemy god (though preferably the ADC) by CCing them. At this time, you want to switch targets from the minions to the enemy god. You want the Support to hit the opponent first to draw minion aggro. If your level 2 ability is a movement ability, be cautious about using it aggressively, as your main goal is to survive and gain pressure on your opponent.
In a case where you lose the level 2 race or your Duo's level 2 does not provide strong aggression, you and your Support will want to be positioned defensively, and may even want to fall back out of range behind the archer line. You will be the likely target of the enemy Support, so you need to determine proper positioning if you see them approaching you. If you feel safe enough, you can attempt to finish more minions to reach level 2, otherwise you’re better off backing off to not get CCed and severely poked by your opponents. During the retreat, you'll want to maintain proper range to prevent getting hit by CC, but this can also give you an opportunity to get in a few basic attacks on the enemy Support to dissuade them from continuing to pressure. Your Support may also try to help by drawing aggro, allowing you to do some damage on them and/or retreat. However, they will also not want to take much damage at this point, so don't rely on them to save you.
In Xbalanque’s case, he will most often lose the pressure from the first wave, getting him pushed close to his tower. This will often mean you won't have to deal with a level 2 fight, as you'll be playing defensively near your tower the first few waves. It is possible even when you lose the level 2 race that your Support starts a fight when all players are level 2, as your opponent takes a long time to get back to their tower and your Branching Bolas will often passively poke your opponent. His level 2 is also not aggressive, as he really wants all 3 main abilities for better damage potential and control, so it’s typically best to play defensively at the start.
Note that during this time, it can make it advantageous for the Jungler to rotate for a gank, if the enemy has pushed up near your tower, making their retreat a lengthy distance.
During the rest of the early game, your primary focus is to farm the waves and secure the Void and Alpha harpies between waves. Keep a close eye on the positioning of the Supports as fights may be initiated at any time. Also keep an eye on the minimap for possible ganks. In cases that you out-pressure your opponent, you can try and go in to steal their Void and Alpha harpies after clearing their minions, but you should only do so when they still have to deal with your wave and are pushed back near or under their towers.
Mid Game
During this phase, the Supports will have usually started to rotate into the Jungle and other lanes, allowing the ADC to farm more efficiently to gain levels and gold. You will find yourself 1v1 against the enemy ADC. Depending on matchups and how the early game went, you can be winning, drawing even, or losing lane. Identify your situation accurately and adjust your playstyle accordingly. Your main goal during this phase is to keep farming, but depending on the situation, you may attempt additional actions.
If you’ve been winning the lane, you can attempt to maintain pressure by outclearing the minion waves, and poking with basics and abilities when possible. If you know you’re safe, you can try pushing them back under their tower and forcing them to lose some farm, or damage them enough to force them to back. If you force them to back or you get a kill, you may consider going for the tower or the Gold Fury with teammates. Remember to ward the nearby Jungle to avoid getting ganked when you’re farther away from your tower.
If you’re at a stalemate, you can consider calling for a gank to tip the pressure in your favor, or if you’re not confident in fighting and the enemy has strong poke, focus mainly on continuing to farm.
If you’re losing your lane, and especially if you’re behind in levels, your safest bet is to continue farming as close to your tower as possible to avoid being caught out and ganked.
No matter which situation, be careful during this phase to keep up wards and proper map awareness to prevent being surprised by the enemy Jungler or Support, turning your 1v1 into a 1v2. Also keep an eye on the minimap to see if any fights in the nearby jungle break out; you may consider rotating to try and help your team out. Keep in mind that your main focus is still on farming, so make sure you can get some kills / assists out of it, and won’t die yourself, as this can make you lose your lead or push you even further behind.
With some more levels in your Branching Bola and your basic attacks clearing faster, you can try to outbox the enemy ADC. Keep in mind that you can also help your team even if you stay in lane while they're fighting elsewhere. Your ultimate as global effect on the enemy, and that blind can disrupt the enemy enough to turn a fight in your team's favor, or help them escape a deadly situation.
Late Game
At this point in the game you will be mainly grouping with your team to secure objectives on the map. Sticking together is important in any teamfights.
During teamfighting you want to position yourself in the backline, behind your tankier teammates and at range of your opponents. Your goal during a teamfights is to dish out a lot of damage, and the way you do this is by staying alive as long as possible. To help achieve these goals you can remember the next 3 rules:
- Focus the closest targets in range: During most teamfights your opponents frontliners will try to get into the backline to disrupt their damage or even kill them. The reason you want to focus on closer targets instead of the most damaging targets is that you will be severely out of position if you try to go for the damage dealers, as they often are in the enemy backline. Your goal is to try and be as safe as possible while doing damage, therefore it can be more beneficial to kite/backpedal that solo laner that is trying to kill you.
- Focus the most threatening target: In cases where multiple enemies are trying to attack you, prioritize the enemy that is the highest threat for killing you. So if the Jungler and the Solo Laner are trying to kill you, you will want to try and kill the assassin first as they will kill you more quickly.
- Focus the more easily killable target: If you have 2 targets of roughly equal threat, your best option is to focus on the one that is easier for you to kill, due to either lower health or low to no mobility.
After winning a teamfight (and hopefully killing multiple enemies), your main objectives will always be to focus on objectives. If you’re healthy enough, go after any nearby towers or phoenixes. If enough of your team is healthy and you know the enemy is either dead or is low health and has to retreat to heal, you should prioritize killing the Fire Giant. Be mindful of respawn timers and your health, and don’t overstay trying to push an objective.
Remember that, as an ADC, you typically have lifesteal from items like Devourer’s Gauntlet or
Asi, and you can heal up quickly by attacking minion waves and jungle camps.
Devourer's Gauntlet. Lifesteal, sustain from potions and nice extra damage on basic attacks, everything you need in the early game.
Hunter's Blessing
Spiked Gauntlet
Healing Potion
Multi Potion
Ninja Tabi is also part of the core items because, since he doesn’t have any attack speed boost in the kit, it’s very important to gain attack speed bonuses from items.
The Executioner
Aegis Amulet
Purification Beads
Odysseus' Bow
Bloodforge
Demon Blade
Poisoned Star
Rage
Deathbringer
Malice
Qin's Sais
Toxic Blade
Titan's Bane
Ichaival
Elixir of Speed and an additional item of your choice.
Y
Transcendence, don’t forget to toggle this ability during long team fights or when walking around. Late-game, the high mana cost combined with high attack speed means you will burn through your mana quickly.
Ares’ 
No Escape, 
Artemis’ 
Calydonian Boar, or 
Bacchus’ 
Belch of the Gods. It can also be used to set off certain traps like 
Transgressor's Fate to clear a path. Do keep in mind that the immunity kicks in after the dash.
Scylla and 
Thanatos.
- PandaCat (Trans): https://www.youtube.com/watch?v=e3gbAm2LqgI
- Another Panda example: https://www.youtube.com/watch?v=s7waituKvKM
- Incon (Devo's): https://www.youtube.com/watch?v=LI_e7pruaaQ
I did write situations in the body where you might prioritize