Kettlebells ~
Kettle
Bells
~ Kettleballs
~ Kettle
Balls ~
What is a Kettlebell?
What Size Kettlebell Should I Invest
In? 
Traditionally, kettlebells only came in 3 weights: 16 kg
(36 lbs), 24 kg (52 lbs), and 32 kg (70 lbs). Now days they start
out a lot lighter and there are many weights in between. All this
choice of different kettlebell sizes can be perplexing.
First off, don't think of kettlebells like
dumbbells. You do not need a bunch of them in 5 lb
increments. One kettlebell, if chosen properly, can last you a
long time. I took a 24 kg (52 lb) kettlebell with me to
Afghanistan for a year and it served my fitness needs well.
For an average female with not a lot of fitness
experience, it is recommended to start off with an 8 kg (17 lb)
kettlebell. Stronger than average women can start off with a 12 kg
(26 lb) kettlebell. Don't go lighter than the 17 lb one unless you
have some specific physical issues that would mandate a lighter
kettlebell. Most kettlebell lifting is done using a large number
of muscle groups, so you can make use of the heavier weight. You
won't be doing bicep curls with it.
For men, most should start with a 16 kg (36 lb)
kettlebell. If you are a bit stronger than average, start out with
a 20 kg (44 lb) kettlebell. If you are a lot stronger than
average, start with a 24 kg (52 lb) kettlebell. Same advice
applies to men regarding starting out with a kettlebell lighter than 36
lbs. I don't see the need outside of an unusual circumstance.
Once you have all the basic moves down and are really
comfortable working with your kettlebell, consider buying the next
heavier size, and/or adding a second kettlebell of the same weight in
order to do kettlebell exercises involving both at the same time.