Okay, this is just a simple build, rush your E then your W then your Q always getting your R when possible.

I've been playing Kayle for a while now, not recently in the past couple weeks, I've been trying a few others I really have an itch to play right now :P But Kayle is amazing at shredding armor off high amount of health champs as well as crushing their armor. I hope you enjoy my build, I'll eventually make more builds when ever I get bored :P

Pros:
Amazing damage mid/late
Slight speed buff from her heal to get out when needed
Heal for both herself and teammate
Amazing clutch saving ult
Slow
Amazing help in teamfights with splash damage knocking enemies down

Con:
Slow start in beginning if you're new with her
She can be ganked easy with no ult
She can't solo baal runs in hell difficulty mode :\

For my masteries I go 9-0-21

I've fiddled around with different items and different style builds for Kayle and found that this is a pretty good choice for her, I have always done great with her on this build. Please feel free to try it out.

Farming with Kayle is a breeze, once you have your splash damage from your 'E' you're set. Just keep using your 'E' on the creeps and rack up your CS with ease.

Kayle is great in teamfights, make sure you enter a teamfight with your ult up. When you see your carry getting dropped hard clutch save him with your ult. I promise if you do this, you will have most likely just saved your team in the teamfight. They won't care to appreciate your amazing Kayle skills, but you don't need their approval!! >:)

Laning as Kayle is amazing, you have that nice heal, nice splash and your attack speed should be coming along just great, so you and who ever your partner is should be doing just fine. :)

At level 1 all you have it you follow this build, is your Q. Which is nice for the slow.
If you have a good laning partner that only needs you to slow and help out then be my guest at initiation, but either than that I'd wait on your E. Once you get your E you can spam it, you'll be wrecking the minions and racking up your CS. Usually as well when I get my E to level 2 I start harrasing them. Your W is the last to get with the small boost it gives for chasing or running, it's heal isn't very high unless you build hybrid or full support lol.

Exhaust/Flash - I use this combo the most, it really suits her well I think personally. Until the new patch when flash gets nerfed, at least lol.
Ignite/Flash - I've used this combo plenty as well, I get this only if I am playing ranked really, and only if they have really heavy AD champions as well.

Just try my build, please feel free to leave feedback for it, I'd love to make it a top build for people wanting to dominate with Kayle. Like I've said, I've played Kayle a lot and really enjoy her game style, she can be a real game changer late in the game with her amazing ult! :)