I sometimes use a "layer mask" at the end of a painting.
This is a small tut.
Layer Mask Tutorial (http://www.trimoon.com/html/layer_mask.html )

Very, very, nicely done, Steve.

A great finishing touch.

Simple, clear, vert well done. Thanks, Steve.

Very well done, clear, simple straight forward directions, excellant tutorial.
More please. . . . . . . . .

Your work is absolutely beautiful. Thanks for sharing - I am very new to this and so grateful for all the help your tutorial's offer.
Jean:)