Not sure how deep into it you are yet but some tips for really new painters:
> Don't skimp on paper
I tend to buy cheap versions of things to try them out and see if I even like the medium before dropping more cash for the nice stuff. This works great in most cases and is fine for cheap water color paints, but you can't skimp on water color paper. Painting on paper that isn't at least 140lbs and wasn't meant for a water medium will be painful. Cheap paint can look okay on nice paper, but even the nicest paint will look like crap on bad paper.
> A lot of effects from from the wetness of the brush versus the wetness of the paper
So experiment with all variations of this. Use a bone dry brush, a sopping wet one, dry paper, paper that was wet before you put any paint on it, and all the combinations in between.
> If you haven't done a lot with color before or are coming from a digital art background then read up on how to mix pigments
It's not the same as picking colors digitally, and although you can mix a variety of colors from just a few paints, choosing different palettes will give you drastically different results.
> Make color and glaze charts for all the palettes you use.
Related to the last point. These can seem boring at first but are actually very helpful and give you a lot of insight on your colors. Google will explain the details of how to make them better than I can. You can also see how opacity and granulation affects mixtures, which can help you get the effect you're going for.