One advice you'll hear over and over again about art supplies in general, and watercolor paints in particular, is to buy the best you can afford at the moment (it's preferable to buy few, but high quality supplies). To put it simply:
Don't waste money on cheap paints!
When starting to learn watercolors the temptation is to buy cheap paints, after all, you'll be producing crappy works that will most certainly end up in the trash bin; it would be a waste to use expensive paints on that.
The problem is that cheap paints have low quality pigments with lots of filler (paints are made of the pigment that gives them color and a filler or binder that gives them consistency and binds everything toguether). This will make color mixing - one of the fundamentals in painting - hard to master because dark values and rich, vibrant colors will be difficult or even impossible to obtain. As result, you'll get frustrated!
There is also the temptation to buy large sets because the difference between a 12-set and a 24-set of cheap paints is not that big. The truth is that to start you'll not need more than 6 to 12 colors; for instance, if you start with a beginners book like Watercolour for the Absolute Beginner most of the exercises require no more than 6 colors: three primaries, one green, one earth tone and a neutral tone.
So, what paints should you get?
Watercolor paints come in 3 grades which are, in increasing order of quality and price: scholastic, student and artist. You'll want to start with at least student grade paints from a well known brand. "Well known brand" is key here because you may find paints labeled as artist grade that are as bad as scholastic grade paints.
Cotman Watercolors from Winsor & Newton are student grade paints widely accepted has having a good price/quality relationship, and easy to find worldwide. Van Gogh from Royal Talens are also student grade paints which, according to some, are better than Cotman but seem harder to find in some locations.
Some people argue you should start with nothing less than artist grade paints. One of the arguments is that if you start with student grade paints and then transition to artist grade paints you'll have to relearn the color mixing part in order to handle the better, more concentrated pigments that these paints are made of. I guess that following or not this advice depends on how serious you are about watercolors and on how much you have to spend or are comfortable spending.
Regarding the number of colors, if you choose student grade paints I advise a 12 color set like the ones in the image above. If you opt for artist grade paints I advice a 6 color set. These starter sets offer at least one of each of the primaries (red, blue and yellow), greens and earth tones; you can then, as you learn, add new colors and replace the ones you use the least.
- Don't waste your money on cheap paints;
- Start with student grade paints at least, artist grade if possible;
- Start with 6 to 12 colors and then add or replace colors as you learn.