kettlebell weights?

mpmama2re

how do you choose the correct weight for you?
I just did a 30 min workout with a 20# kettlebell and a bob harper kettlebell dvd. while it was a litte hard I could pick up the kettlebell over my head with one hand and do the reps. But is 20# to high to start with. I really don't want to hurt myself. and my back is aching a little right now. I really like the kettlebell work outs but those kettlebells are very pricey so I'd like to have the right one.

also I am 5'4" and 131# if that matters.

rawfitness

I usually start my training clients with a 15lb KB. It kind of depends on the exercise too.