Here are a few of the tools that I have:

Hex Codes This is what you can use to find out the colours of things

Ro Skin maker. This is what you use to actually make the skin. Template is included. The information on how to make it transparent is on RoEmpire

Ro Skin Viewer in English The Viewer to actually see what your skin looks like instead of always having to log into the client.

Later I will post more, when I can think of others.