Step Two: Make sure you change the image to RGB Color Mode.
So you can use any colors you want. Otherwise you will only get the colors related to the base colors.

Step Three: By now you should have a general idea of how you want to dress your doll.
I decided that I want here to wear a nice sexy dress.
smallest size 1px

Step 4: Select a the darkest shade of the color you want the dress to be.
The Dress I am making is red so I choose the darkest shade of red from the swatches palette.

Step 5: Create a new layer. And us this to make the outline of the piece of clothing. It is best to use a new layer in case you make a mistake. The base is still in its original form.

Step 6: Make an outline of the dress or clothes you are making. if you are making a shirt n pants it is best to make one piece at a time then the second piece. Make sure you leave no open spaces.

Step 7: Now select a liter shade of the color this color should be medium. So you can make one shade that is a little darker but not as dark as your outline and one shade that is liter. Now using the full tool fill in the inside of the dress.

Step 8: Make an other new layer. Using as shade of the color that is a little darker then the inside of the dress but not as dark as the outside you want to make shaded areas on the dress. It is best to make these areas where you think it will be naturally shaded on a real body. This also allows you to give your base from if it has none. 

Step 9: Make yet an other new layer: It is good to use new layers for each step. So if you make a mistake. you don't mess up anything you have done already. Also this is probably a good time to save your work. Now using a liter shade go around the out side of the part you have shaded darker. It is nice to use the airbrush tool for this because it helps it blend better.