1) Don't start with shading.
Start with blocking in the base colors. Once you're done with that, darken (if you have that tool) eye drop and color wheel for somewhat hand-picked colors (if you have that tool) or completely hand-pick colors. Make sure you create a realistic, clean gradient. Make sure you consistently use the same style, or your skin just won't look right.
[b][color=#0000FF]2) Plan[/b][/color]
If you don't plan your skin, chances are it won't be as good as if you did plan. Make sure you have a good straightforward idea. After you have a good skin in mind (maybe even a sketch if you're that motivated) draw your skin in whatever program you use.
[b][color=#0000FF]3) Pick Good Colors[/b][/color]
Make sure you pick appealing colors. Nobody decent will want a skin with dark, gloomy, and overall disgusting palette. Nor one with too vibrant of a palette. Pick a good, pleasing palette if creating an original skin. Think back to your plan in this step. Your plan should include a decent idea of the palette that would look best with this skin. Try not too make it too all over the place, but consistent colors that go well together.
This is really basic and probably didn't help you, but hey, they're still considered tips.
