PROS :P CONS 3:(
.easy to play .Troubles to take down tanks
.easy to get fed with .weak to constant pokes
.isnt band in ranked .Hard Crowd Control
.lots and lots of damage
.can be build (AP/AD/HYBRID)
.easy escape

Your skill sequence should go a little something like this. Counter strike so u can activate sheen's passive (spell blade), then Empower for extra damage and then jump to them to maximize effect. then if you are vsing a high sustain champion like Vladimir, Aatrox, or Swain active ur ignite just before they come off stun so they cant just heal back all your damage. remember to activate your ultimate if you feel you need the extra magic resist or armor. with this sequence you should follow up with some kills

Jax has no troubles farming because of counter strike and his passive make it really easy however it is also very easy to push the lane further than expected so try and last hit but not so much that he doubles your cs. also i do highly recommend u do not recall when there is a Siege minion in the lane to get that extra gold unless it could cause you to die while trying.

all in all jax is very easy and even if you don't do well early if you keep trying you can see yourself to come back in mid game to them become unstoppable late game. i hope you enjoyed my very first guide and if this gets good feed back. i will put more effort into my other guides and will make more off them.