I'm occasionally asked for advice on watercolour. Not that I consider myself the greatest watercolourist or anything, but I've been using the medium almost daily for years, so I've picked up a few helpful pointers along the way. I thought I'd share a few hints and tips for the beginning watercolourist (and then when I get asked "how do you paint in watercolour like that?" I can just give them the link to this News Articl). .

1. The Rules
Forget them. A watercolour purist will tell you never to use black and never to use white. This is patently nonsense. They'll tell you "you must make your own black, and use the paper as your white". If you know the history about why they made up these silly rules, you'll see why you ought to ignore them: the notion of not using black watercolour started because good blacks were unavailable after whales became scarce.
Hunh? It's true. Ivory black was originally made by burning whalebone. When whalebone became virtually unavailable, black was hard to come by. That's when the "rule" started. Then they discovered that you could scrape the goop from the inside of hurricane lamps - and Lamp black was born. But the "rule" persisted. (My thanks to Benjamin Moore Paints for the history lesson, by the way...).
As for white, I use the paper to serve as my solid white in paintings, but white watercolours make a great mixer. Skin tones appear creamier, and white softens other harsh colours as well. I don't use it as a colour on its own, but it's actually quite useful as a mixer.
A lady who fancied herself an expert actually quit one of my watercolour classes because she thought I was speaking blasphemy when I told the class that using black and white were okay.
Another dumb rule is "always work from light to dark". Ignore this rule. The reason they'll tell you this is that you can cover lighter colours with darker ones, and the hint of the lighter colour will show through. That's fine, but not always the way to go. Particularly with portraits, I almost always start with the darkest colours and work to the lightest. This allows me to use the moisture in the lighter tones to soften the edges of the darker colours as I go - I avoid lines between the colours by working "backward".

2. Get an arsenal of various brushes and know how to use them.
For that "fuzzy" effect that watercolourists are so charged up about, you'll need a fat brush that holds a lot of water to do a "wash" - that is, wetting the paper before applying the paint. Get a fat round brush or flat brush for that. Great for backgrounds. (Don't always wet the paper, by the way - you'll need dry paper for sharp lines and detail).
A lot of watercolourists use fan brushes (or "grass" brushes) for hair and grass - very useful item. It's the one shaped like a fan.
Get a nice fineliner if you want to do a lot of details - I recommend spending the money for a nice one, but then, I use mine a lot. The tiny ones with longer bristles are harder to control but make finer lines.
A nice little flat brush or angle brush (also known as a "chisel" brush) makes great wider straight lines. I use the flat edge of the brush for this - that's how I do hair on my people portraits.
Particularly if you're going to paint furry animals, I recommend a small ruined flat brush - one where the bristles have seperated. The effect is much like a fan brush, but creates much smaller lines and is much easier to control. That's how I get the fur on my animals. Don't have a ruined brush? Give one to a six-year old for twenty minutes.
A toothbrush. You'll need it - trust me. You can use it to "shoot" the paint onto the paper with your thumb. Great for sand, stars, dirt and freckles (but mask anything you don't want spattered by covering it with extra paper).

3. Tubes or cakes?
Watercolour comes in two forms - tubes (like oils) and cakes. I usually advise avoiding watercolour right out of the tube because if it's wet, it's harder to determine the amount of water versus paint is on the brush. The longer you fiddle with the brush in dry paint (like cakes), the darker the colour will appear on the paper, and it's easier to control the proportion of water to paint on the brush. If I buy tubes, I always let them dry on my palette before using them.

4. How much water?
This is the hard part. I tend to use just enough water to keep the brush damp - too much water causes puddles and creates the potential for runs and bleeds. For washes, I usually use just enough water to make the paper damp, and do the wash in sections...quickly, to avoid "drying lines". Again, the longer you fiddle with the brush in the paint, the darker the colour. A lot of watercolourists "test" their brush on scrap paper before applying it to the painting, but that "releases" the paint from the brush, and your next stroke is going to be lighter than it is on the test paper. I usually just "wing it" and if it's too dark, I just moisten the brush with plain water and take a bit of the pigment away. As disgusting as it sounds, for those nice dark colours, I like the paint to have a consistency almost like blood.

5. Erasing
Whoever invents a watercolour eraser is going to make a fortune. Generally, once it's dry, you're pretty much stuck with it, but in an emergency, I use a small stiff-bristled oil brush and clean water to lightly scrub away mistakes. Lightly is the key - if you scrub too hard, you'll damage the paper. It's generally best to work through the mistake or try to hide it rather than remove it.
Believe it or not, you can erase light pencil sketches that are under watercolour paint with a kneaded eraser. Don't rub the bejeezus out of it or you'll remove the paint, but it's great for light erasures of your sketch. That's why my paintings usually don't have very many pencil marks.

6. Buying the paper - is "good" always good?
Nope, it's not. It depends on what you want to do, really. Generally, the better paper is indeed better and worth the investment. I've found that 300-pound Arches cold-press (that's really good paper) is great for some things (wonderful washes, for example), but the el-cheapo 90-pound junk you can get at the Wal-Mart has it's advantages. Because it's cheap, it doesn't hold the paint well. Hunh? Yeah, that can actually be helpful, because you can move the paint around with water a lot easier on the cheap stuff. This comes in handy when making harsh lines softer. I use the technique a lot with hair to make it look furrier or softer - the heavy harsh lines don't look very natural to me as far as hair goes, so by running a damp flat brush over hair lines, I can soften the look. And the cheaper paper makes that a lot easier.

7. Mixing colours
I usually start classes by having the students practise mixing colours on a sheet of scrap paper and then writing the names of the mixed colours next to the result. This gives a good "guide" to the beginning watercolourist for future paint mixes. If you need an olive green, just look on the "guide" - ah, sap and yellow ochre. I usually just mix a bit at a time, and never right out of the tube. What do I do when I run out of the mixture? Just make more - and if it's slightly "off", I don't let it bother me. The subtle variations in tone are usually a good thing - they give the painting more depth.

8. Work in sections.
As one area of the painting dries, you can work on other areas. A lot of the elements of paintings fit together like a mosaic - by working in one section and then another while the first dries, you can avoid runs and bleeding. Putting one wet colour right next to another wet colour is only going to cause heartbreak and frustration. Wait until that first colour's dry.

Well, those are the basics - I'll add more if I think of them. Other watercolourists will tell you different things - it's not that they're wrong, they just do it differently from me. But as I say, I get asked "how do you do that?" a lot, and I thought I'd share how I do it, anyway. If you have any questions, I'm always happy to help.

My animal paintings:
My people paintings: