I agree with NOO nickname, lately I've been doing whatever role on league just because but I did main adc's in ranked and had a lot of success
**Practice farming, make a custom match with only you, take off your runes and masteries. Try and get 100 CS by the 10 minute mark. If you can average about 75-90 CS per 10 min you'll do much better in the match. Most LCS players have 200-300+ CS by the end of the game.
Kiting is super important, practice moving away from a target between shots. Shoot, move, shoot, move, shoot, move. It takes practice but if you can master it then you can do significantly more damage.
Postioning. It's important to stay behind your front line, You're the ADC you should be doing a large amount of damage, and if you've been laning well, the focus will most likely be on you. stay behind your tanks support until you can reach the other team, preferably after they use their ults and CC/engage abilities on other champions.**
ALSO AS A JINX player myself. Jinx naturally has large attack speed based off her Q ability passive. It's above 1.0 a second at level 5 without any item enhancements if you build a classic rune and mastery page for her. So this gives her the advantage in the instance that she doesn't need to build an attack speed item until her berserker greeves. Rush one AD heavy item, then a second AD heavy item while buying
By the time you finish all three of these items you'll have nearly about 1.5-1.9 attack speed. But you'll also have more AD than what other champions.
One big thing about Jinx too is that she only gets that attack speed boost from her Machine gun, which has lower range, so if you build these items, you can take on most champions.
You'll have a counter item to assassins, and to tanks. You'll have High AD with a good amount of life steal BUT your Runaans hurricane almost triples the healing when your in machine gun mode because all of your shots will be shooting out other bolts that will both crit on enemies and heal you for that damage. Along with these you'll also have 250% bonus damage 50% (maybe 60% i forgot) crit rate and you'll shoot 2 times per second.
You'll heal a ton, do a ton of damage, and counter assassins/mages/tanks it's an easy build to win with
Try building the 4 items first if your team is ahead, if you're behind, rush one of the counter items first depending on which enemy champion is causing the most damage against you/your team.
Hope all that could help, if you'd like to do a few matches let me know and we'll go over some other laning phase stuff you can do with jinx, like aiming at the ranged minions with rockets to both kill them and poke the other ADC.