i like software to color because i dont have to commit to it although i have a desire to start working with watercolors but i have to be pulled out of my comfort zone somehow.
First of all, I think coloring in PC looks very artificial to the human eye. Secondly, I intuitively trust the ancient Aztec belief that only in real pains-taking human labour lies something of a value, substance if you like. But enough of philosophy! :)
You could bye a bunch of good markers if you're afraid to experiment with paint.
But if you'd like to use watercolor, I would suggest buying quality paper (Arik Roper uses Canson/ARCHES 300g watercolor paper - cold and hot pressed, I've found it to be quite the shit), mount it on a board (research hat shit, its important also), some good brushes (shitty ones are useful too sometimes, for creating patterns etc....) and obviously some vibrant watercolor's
Another way might be painting cel'
s on top of a line work, like they did in the old anime/animation times (I think they still do it in Studio Ghibli heh), I tried acrylics for this and it had some really interesting results, especially lighted/above a lightbox....
I prefer acrylics anyway, as they give a plastic effect which is really a whole another dimension of ... uhhhmm.. artwork making
You can create things with a single brush stroke that would otherwise have to be drawn painstakingly.
Watercolor on the other hand has its advantages too, especially for making backgrounds etc, as colors can blend in wild ways. But the disadvantage is that its hard to control/manage (at least for me).
Here's a really good presentation on a lot of different kinds of watercolor application:http://youtu.be/wbDawbOO8XY
Btw, the old rennasaince masters like da Vinci, Botticelli,.. used tempera for cloth and backgrounds and oil for skin, so combining different kinds of paint is also a think to consider.
The most important thing I've learned, which no ene ever told me haha, is that you need to take really good fucking care of your brushes! You need to give them the TLC — Tender Loving Care ;), if you want them to stay the same as when you bought them. Its kind of a fetish for me right now :)
Woah that came a bit too long, but hope it helps a bit
Good luck ;-)