At what part of the application process did you tear the decal?
I'm still relatively new to decals compared to some, so its still a learning process. Here's what I have done with success so far with applying decals. I shoot a clear coat on the body before applying any decals.
1) Use the proper tools to apply decals...makes a huge difference...
1a. Decal scissors...I currently don't own a set, but I did abscond some scissors that look like something a surgeon would use...they do cut close to the actual decal and CLEAN , no jagged edges.
1b. Decal tweezers...I got mine from Micro Mark...yes, they are designed different than any other tweezers.
1c. Decal blotter...blots excess water from the decal....available from Micro Mark...a must when using setting solutions.
1d. Setting solutions...I am currently using Microscale Micro Set and Micro Sol. The model rail roaders swear by Walthers Solvaset, there are some other decal solvents out there as well.
2) Wash and rinse the body....I use Dawn dish washing soap to get rid of any oil residue that still maybe present on the body. This is particularly important with a resin body...even if its been painted. Some older styrene bodies will also have secreted oil residue due to their age.....i.e an 80's Monogram NASCAR body....an obvious sign of this is that the body presents itself to being brittle in an extreme case.
3) Allow the body to air dry....avoid the use of towel drying to help prevent unwanted particles from attaching themselves to the body. If you can, place the body inside something to prevent dust and hair particles from settling on it...I use the toaster oven in the hobby room.....OFF and cool of course!
4) Using a detail brush,apply Micro Set to the area where the decal is to be placed. This softens the decal and improves adhesion.
5) Cut the decal from the sheet and place it in the water...I try and use as little water as possible...usually 30 to 45 seconds is all that is needed.
6) Remove from the water and place the decal....I use the decal blotter to move the decal into place.
7) Blot excess water away.
Once all of the decals have been applied, I use a detail brush and brush Micro Sol on the decals. This softens the decals to conform to irregular surfaces...give the decals a painted on appearance.