Follow this very detailed guide to learn how to play Jinx. I got ya.

To lane successfully, you must know if you should play safe, or aggressive. If you have a Leona support, then kill all the creeps as soon as possible to get level 2. Once you and Leona are level 2, then engage on their squishiest champion in the bottom lane. It should be a free kill.

Play really safe if they have an Alistar support. He can easily flash, Polverize and then Headbutt you to their turret.

If they have a blitz, then keep the wave even. This means, if their ADC is freezing, then you should freeze too. This allows you to hide behind creeps to avoid getting pulled. If their ADC is pushing hard, then allow the creeps to come to your turret and you can safely farm under the tower behind your fresh minion wave.

If your support goes back, and you are the only one in lane against 2 champions, then BACK THE **** UP! You will die if you WALK UP TO LAST HIT!!!! Let the wave push to your tower. If you walk up to last hit alone, they will take advantage of this and stun, or pull you and kill you.
Respect the 2v1 you fool.

Another mistake is DIVING for the low HP champs. If their champ has 10 hp left, and you're at 20% HP... do not dive their tower if you know you're going to die for it. Just farm the creeps, push the wave and recall! They lost so much experience just from recalling, but you, you could probably clear 2 waves of creeps and have a level advantage for the next fight.

Another mistake is, do not go for creeps that you will get harassed, pulled, or poked for.
Go for the creeps closest to you. Don't let them poke you just so you can get 1 CS. You can always get more creeps later on.

Stay in the back in teamfights. Attack the closest target to you. You shouldn't take damage at all. If their bruiser like Renekton, or Darius, or Jax, goes for you.. then kite backwards, and kill him. If they have an enemy Vi, or Zed, then DO NOT LET THEM SEE YOU UNTIL THEY USE THEIR ULTIMATES!!!!!!!!!!!!! Start attacking once you see them use their ultimates.

Use your Rockets to farm huge waves of creeps. GG

Peace.