Kettlebells purchase can be tricky
Make sure you got nice smooth handles and rounded ones. Some companies are selling "pro models" with grippy handles looking like barbells and that would suck balls!
You don't want square handles either...
Depending on your size start at 25lbs or 35lbs
I'm 135lbs soaking wet 5'8 and I started with 35lbs and it was a pretty intense workout but blasted through it after a couple of weeks.
Now I'm doing all my routines at 44lbs and a couple of exercises at 53lbs
It's all about technique! Once you figure out to move yourself under the weights and such you'll be able to swing heavy weight in no time without fucking yourself up
Plenty of DVD available on the interweb but I'd recommend Pavel Tsatsouline/ Steve Maxwell and Mike Mahler. Those guys are legends in this field