Here's how I usually go about making my textures. I'll open my character in the BrawlBox preview and work from there. As I'm making making edits to the text and I want to see how it looks, I'll replace the texture (while still in the preview mode). This allows me to see how my changes to the texture effects the character.
What I usually do when I don't know where something is, or I want to know what a particular thing on the texture sheet does, I'll make a new layer (I work in GIMP) and color it all kinds of random colors like this:
Then I preview it in Brawl Box to see something like this:
This allows me to see which part on the texture goes where. Now I know the part I colored white effects his clothes and the part I colored yellow effects his gloves, and so forth.
And since I did this as a new layer, I can now delete (or hide) that layer and continue to work on my texture.
I may make a thread explaining some of the other useful texture techniques that I use as well.