Armorama has an article on using washes to weather your armor models. While its intended for plastic modelers, it also is great advice for 15mm and 25mm – 28mm gamers. I’m not so sure that it would be useful for anything smaller, though.
Painting
Painting Faces
This is a nice tutorial on painting faces on your miniatures. It’s probably over-the-top for painting armies, but for character pieces …
Making Oil Washes For Your Miniatures
Here’s a set of instructions for making oil washes for your miniatures. One key that I had not thought of is to first gloss coat your miniature for a smoother surface over which to put the wash.
I am seriously going to try this on my next batch.
Make Your Own Dip Washes
“The Dip” is a fantastic way to make moderate to poorly painted miniatures look great. Or to turn a basic block painting job into one that looks like you knew what you were doing. This video has a technique for making your own.
How To Make Washes For Your Miniatures
Luks Aps has a video on how to make your own washes. As teh commercial washes are fairly expensive, this is a good method.