applying decals

Hi there! I haven't used decals for a very long time and was hoping that you could tell me how, and what products and tools you use to apply decals. I will be trying it out on some elder pretty soon.
I have decal fix and am not 100% sure how to use it. any advice?

thank you for all the help

http://www.youtube.com/watch?v=R7Ywau87mo4

is this what you mean?
Hopefully the video is helpfull, I never used the stuff.

Yes thank you. I tried this out with a coat of decal medium after I placed the decals with decal fix