Watercolors can be an awesome medium if you know how to start, and a horrible experience if you do not understand how they work. Here's how to start mastering their use.
First of all, start small. You do not need to go out and purchase the most expensive watercolor set to get started. As you become more comfortable, you may want to invest in graduated levels of paints. I suggest a cheap set of children's watercolors, but buy a different brush. If you spend anywhere, spend on a brush.
Brushes can be more expensive than paint. Michael's Craft Stores often have their brand of paint brushes for short money. You will need a round brush for watercolors. Round brushes hold water, an important feature if you are using what is essentially a dry medium. I like a number 9 round brush to start. It's large enough to make it useful, but small enough not to intimidate a first time user.
Ironically water is the missing ingredient in watercolors. While it is ok to wet the brush and then rub the color onto it, I find that damages the brush. If you decide to go further than a test drive with watercolors, you will want a spray bottle to wet the paints instead of using a brush. The best sprayers I have found are the small travel sizes used for TSA regulations when traveling. They are inexpensive and last a long time.
You will also need a jar or other container for water to rinse the brushes out. I like an old bouillon cube jar or small jam jar. Something that can hold about a cup or two of water is ideal. It should be heavy enough so it doesn't tip if you bump it. You may want a dish sponge or paper towel to daub your brush before applying the paint.
The last ingredient in this art soup is paper. Like brushes, you want the best watercolor paper you can afford. Ideally, the paper should be at least 140 lb. and specifically made for watercolors. Again, Michael's Craft Stores and other craft stores sell their brand for a reasonable price. Where paper is concerned, as long as it is made for watercolors it is safe. Regular paper rolls and buckles with the water. Watercolor paper is absorbent and can handle water easily.
Once you've assembled your supplies, it is time to start. The important thing is to experiment and let yourself play with it. I find it best to play first and look for instruction books later. Most watercolor instruction books are aimed at the seasoned painter. I've been using watercolors for five years and have more fun just playing and taking a few online courses here and there.
If you do try watercolors, let me know over at the Painting forum what you thought!