Photoshop painting tips, 5 ways to find lighter color. For image and steps http://idrawgirls.com/tutorials/2012/... Value or lightness varies vertically along the color solid, from black (value 0) at the bottom, to white (value 10) at the top.
1) Turn the brightness (B) up toward the right side from whatever color you are using. Make sure you are using HSB sliders on color, not RGB or CMYK.
2) Make a new layer on Screen mode, then you can select the base color to paint. When you paint on screen mode with the base color you have, it will automatically get lighter. Though you will have to choose the right opacity, probably in between 30-50%.
3) Make a new layer on Overlay mode, then pick white or light gray to paint with. Overlay will automatically blend your light with saturation on your base color. It is slightly different than screen mode.
4) Make a new normal layer, they you can pick white (with or without saturation turn all the way for the base color) and paint with 30%-50% opacity. You will get a lighter value, but it could give you a dull effect. But if mute color is what you are looking for, this is the way.
5) Use "Dodge" on layer mode or in brush mode itself. Then you can paint with it and get darker value. Follow step 2 and step 3 for detail and effect you will get with them.