Well, when you get to that stage, ask away :cool.
There's no real "secret" way, per se, but there are ways to get more "professional" results. Put down a good gloss coat before decaling. Decals go down better over gloss, than matte. After applying the decal, brush with some diluted white vinegar (70% vinegar, 30% water), to pull the decal down. After that's cured, give it another gloss coat to seal them in and bring everything together.
I just finished working on a 1/72 F9F-8 Cougar in a Blue Angels scheme. She's a 25 year old Hasegawa kit, that had 25 year old waterslide decals :sick. I had to soak these things in hot water - for over a minute - before they would release from the carrier sheet. And when they did, they were cracked. Using the method above, you'd almost never know how bad the decals were. When I get some pictures, I'll post them up.
-Fred