Hi, I'm Pays164; we'll talk about how to increase depth with contrast color. In examples of my piece I used a really bright red or just a really bright color behind all that black outline, to create the depth of 3D and make the letters pop off. You know, any good combination of bright colors on the fill, bright colors on the background with good, dark solid outline will create that contrast to make the letters pop off the wall. In the area of the 3D I did this E and you can see how the back fold comes in between these two bars and with that black shading that was really added to the depth to give the illusion that this is like a box shape that is totally popping up at you.
Both of those techniques are real helpful with creating depth and contrast, just separating your dark's from your lights and putting them in the right place. You'll be able to create a good piece just by taking those colors, dividing them in half and designating what's for the outline, what's for the background, and what's for the fill in.