Cut them close to the pattern for one, and make sure the surface you're putting them down on is smooth. You can do this with brush on gloss varnish like Citadel sells. After said varnish dries, brush on some Microset:
http://www.microscale.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MI-1
Then put the transfer on as usual. With a brush wet with Microset, brush out any air bubbles. Once everything's dry (takes a while) then varnish it. Microsol is also something people use in this process, but I've never needed it. The Microset eats away at some of the non-colored parts of the transfer at the edges and makes it easy to brush out any unsightly air bubbles.