Sometimes the most interesting effect is the simplest. Having a black or white background and then using white over that or another favorite color can produce very interesting results. Also, one might put green or blue on top of red a little off register to give what looks like the old 3d type of thing you view with those special glasses. I usually do this sort of thing in separate layers so I can adjust or delete the effect. When I make a brush, I usually try for a middle of the ground size so I can increase or decrease the size a little when I actually use the brush. Also, most of the time, I don't use 100% opacity for a new brush. A little at a time or use the airbrush to experiment with a new brush. I like the ones that look like old paper or are so big that they take up the whole page. Sometimes anyway. They are fun to get "paper" that looks like a real page or a piece of fabric. Dull, antique yellor or old gold color is nice on black to start with. When I do stuff like this, there really is little need for other special effects using filters and such. Just a few thoughts here before I head off to work. Have a nice day, all.