Women who are new to kettlebell training and lifting in general should start with an 18 pound or 8 kilogram kettlebell. This weight is ideal for a woman who is just beginning weight training whether it be in the gym or at home. Remember, you want a kettlebell you can grow with, even if this seems like a lot of weight at first, you will fairly quickly be able to increase your reps through regular use and the workouts you do. Women who use some form of weights but are new to kettlebells should start with a 26 pound or 12 kilogram kettlebell. For anyone who is going to be using kettlebells, a kettlebell set is great purchase. First because it will allow you to grow with your kettlebells and give you some variety as your strength increases for certain movements, but also because of the heavy discounts which are applied to sets versus individual purchases. It is hard to make recommendations without knowing you specifically, but this is where most would start.