Well, there is a lot different decal paper you can use, you have to get the right paper for your printer, either ink jet, or laser printer.
For the most part stay away from testor's decal paper, I do use it sometimes, but for the most part it sucks, if the surface is not flat, it does not want to stay down. The only upside is I get it at Hobby Lobby using the 40% off coupon.
When doing your own decals, make sure you clear coat them before use, any clear coat will work, I keep a can of krylon clear on hand to use for decals
Not sure if you know this, but house hold printers can not print white, so if need white, you have to get the white decal paper.
There are two main choice's clear and white decal paper.
Here are a few links
http://www.micromark...ecal-paper.html
http://www.bare-meta...Decal-Film.html