this is my first build with any champ, so be nice.
i go jax with AD because of his signature move: Leap Strike.
it scales 100% of AD, so if u get this build finished u will get AD to ca. 550.
pls try it before downvote.

i picked AD runes to get his AD higher hehe, and a little dodge for his ulti.

in masteries i go 21/9/0
21 off: for the extra damage and some extra attack speed
9 def: for the dodge and some magic resist, because u will mostly go after nukers.

i start out with amplifying tome for some AP to leap strike.
then go get the sheen, it will double the AD for the next attack, when u use your Empower, and then baammm, nearly half of the enemys life goes away.
then go get some Berserkers greavers, for some attack speed.
then go get The Bloodthirster for some real AD and lifesteal.
go get a phantom dancer for some crit, movement and attack speed.
go get a last whisper to get 40 AD and hit through their armor.
get trinity force to get the double from sheen to 150%
at last get yourself a infinity edge for some more crit and AD

the skill sequence is: 4 - 1 - 2 - 3

exhaust for dps or to slow the enemy
and ghost to catch the enemy of get away.

first of all if u see an enemy, go to brush near them and wait for them to get near pop ulti and then use empower and then leapstrike on enemy. boom they are half life. if they keep attack and u dodge then use counter strike. if they dont die use empower and leapstrike again. always use counter striker when possible.