One of the questions I get asked the most is about what colors do I buy? Of course you can always buy a kit and 95% of the time these colors will be in that kit. If you are feeling adventurous you can go through and buy the following colors which will give you a good basic palette:
Lemon Yellow
Cadmium Yellow Medium
Yellow Ochre or Raw Sienna
Burnt Sienna
Cadmium Orange
Cadmium Red
Alizarin Crimson
Viridian Green (Thalo or Prussian)
Prussian Blue (Winsor or Thalo)
Ultramarine Blue
Paynes Gray
The other item that is imperative to any watercolor artist (hobbyists) is a palette with deep wells. Any palette will work but if you are looking to paint watercolors on a regular basis I recommend one with deep wells and a lid. You can get these at any craft or art store for around $10 (I paid $4.00 for mine). I recommend not spending much more than that on them. Especially on a plastic one because they do break quite easily.
I also recommend having a Fine Sharpie so you can label the wells as you go. The more you get into watercolor you will understand why the labeling is so important. Many times I have wanted to use Paynes Gray and have dipped my brush in Indigo or Sepia. The other tool I recommend having is a pair of pliers for those stubborn tops. There is nothing worse than trying to get a stubborn top opened.
Another point I want to make is you don’t need expensive paints to make great paintings. In my opinion mastering a more expensive paint especially in watercolors can be quite challenging. I recommend starting with a basic pan of Crayola Watercolors and if you like it then move onto investing in watercolors. Painting is a skill that if you don’t train (aka: paint) on a regular basis you will get rusty. Watercolors should be fun not a burden. Remember I have over 20 years experience in painting (painting or sketching close to everyday of those years – 7300 days I have been painting) so don’t expect to be able to paint like me after the first time or even the 100th time. I have over 7,000 days in experience on you so don’t be discouraged enjoy it that is what painting is all about 
My palette with the color names written with permanent marker – It usually is not this clean
Who Are You Calling Crafty? 