Removing decals

[RichCostello]

How do I do it without messing up the paint?

[Pete J.]

Depends on the paint.  Most of the time a little tape applied to the decal will pull them up.  If you are dealing with lacquer and it won't come up, alcohol will generally dissolve them. Windex is also good if you are using lacquer or solvent based enamels.  If you are dealing with water based acrylics, then just plain water or tape.  Any solvent is guarantee to ruin the paint.

[espo]

Everything that Pete J. said with one small addition. Should the decals be under a clear coat of paint you might have to redo the whole paint job anyway.