I usually repaint the arf's I buy. Mainly because everyone else will have the same plane!. Normally you will want to scuf the area you are going to paint with scotchbrite, steelwool or 600grit sandpaper. You can tape the specific area and then sand and paint. Use denatured alcohol or paint thinner to clean the area and then a tack cloth.
Paint will not normally stick to the covering unless its roughened. To seal decals you might want to try some clear nail polish on the edges. If it comes off later then its just a quick retouch.
After the plane is painted and wrinkles surface then just get out the ole heatgun and fix! The paint is usually pretty flexible and wont come off.