I?m an ADC main since season 6 and finished Diamond II last season. My mechanics suck. I got to high diamond with macro only. I made a video version of the guide and also a text version if you don?t want to watch.
Text version (works 95% without video):
When playing bot lane, you start by covering the respective lower bot side jungle entrance, while your team mates cover the upper entrance. Should they refuse to do that, keep in mind that the enemy team could be sneaking up behind you. If you spot a five man invade, run to safety. Should the enemy invade continue, run again as soon as you see them. If they see you, be prepared to flash away if they flash to catch you. When you are safe again, hug this wall as you walk towards your tier 1 tower, so you can react to a potential ambush. In the laning phase, your most important warding spots are these bushes, depending on how hard you are pushing. Should you be completely pushed under your own tower for an extended period of time, place wards in the jungle next to you, so you can detect ganks from the enemy mid and jungle. Especially when the mid laner is missing and your own mid does not follow, you should keep a safe distance and try to preserve your health pool. Always make sure that there are no enemies behind you. Wait until they leave or until your team mates come to help. Should you be pushed in and your jungler or mid laner try to help, you can fight the enemy close to your tower. If you can?t kill them quickly and they run, let them. Chasing would leave you open to an enemy countergank and also minion aggro might outright kill you. Never fight in an enemy minion wave. Should your tower fall, you can still collect minions in this area. If you extend any farther, you will die. Push the wave to this point and then join your team wherever it needs you. As soon as they start pushing the tier 2 tower, collect the minions, and rinse and repeat.
When you have a rather smooth laning phase, your goal is to force your opponents to recall first, so you can push the minion wave into their tower and then recall yourself to spend your gold. This is how you build up an advantage. If you win lane and take down the enemy tower, push the minions past the river and then roam. Go base before that, if you have lots of gold or low HP. When a dragon is on the map, start pressuring mid lane to keep dragon control. When there is no dragon, pressure top lane instead. Rule of thumb: play very safe in top lane. If your support is with you and your jungler is in top side jungle, you can play aggressively. As soon as all tier one towers are gone, you should always push minion waves past the river and then group with your team. When you need to fight for objectives, it is okay to give up some farm to stay grouped.
Level 9, you upgrade your yellow trinket to blue trinket. Being able to ward from a distance is crucial, as your most important job as an ADC is to always stay alive. Never face check unsafe territory. You see where you can walk safely by drawing an imaginary line between all of your remaining towers. If your towers get destroyed, you also lose parts of your jungle. Everything outside the area is no longer safe. Be cautious! And now you can also clearly see why mid towers are so important. Even when all side lane towers are there, you lose jungle control completely without mid towers. Without jungle control, the remaining towers are easily divable and you need to let them fall when pressured. To get back into the game, place your control ward just outside your safety zone, so you can spot and catch overextended enemies. Stay as safe as possible. You can keep an eye on baron and dragon with blue trinket, but giving them up can be necessary, if you are this far behind as a team. Your best bet is to hard engage as 5 under your inhibitor tower after provoking the enemy into a careless dive. If the enemy splits to bring baron buff to multiple lanes, hard engage as 5 in one lane and win the fight with numbers advantage. You are the ADC and therefore join team fights rather late, so use pings and chat to lead your team.
In a more even game, you play around your fed team mates to pressure enemy turrets. Push mid and bot lane, if the next upcoming objective is a dragon, and push mid and top lane, if you need to prepare to fight over baron. Always put a control ward in the pit before you go for them. When you are ahead as a team, and dragon and baron are already taken, you should push the lane with the most enemy turrets. Doing this grants you more gold and more control over the enemy jungle. If they have two lanes with the same number of towers, push the lane where you have less towers, as pushing that lane will remove pressure from your inhibitor. When your team does not listen to you calls, it is better to stay grouped with them to help in fights. You normally stay with your jungler, support, and mid laner while your top laner creates pressure on a side lane. As the ADC, you are entitled to take all the lane minions and all the jungle camps, with the exception of allied blue buff. Some team mates don?t understand this concept. Let them farm if they are tilted to prevent a rage quit. So during down time in the mid game, your team tries to extend the vision line with wards as far as possible, while you farm your jungle and collect minion waves that crash into your unattended side lane tower. The best spots for placing down your blue trinket are bushes just at the edge of the aforementioned safety zone. Here, they detect enemies trying to invade and give your team the opportunity to react to threat in time.
If a fight is about to break out, you need to move towards your allies immediately. Fights are always more important than farm. Even if you notice the fight too late, you should still start moving. Late is better than never. Against enemy teams with champions that need to one shot you, always stay close to a team mate that can protect you. Sometimes, that team mate is just your closest tower. You go in aggressively when enemy gap closing and crowd control abilities are on cooldown. Taking down an enemy inhibitor before the next dragon or baron spawns is optimal, because they need to clear super minions and cannot fight you over the objective. From here, you again safely push the lane with the most towers, and then rinse and repeat. Or as I like to say: Take the free stuff, win the game.
GLHF and happy climbing:)