There is a great thread on the boards all about decorating magic bands.  I used a clear base and top coat nail polish as a base coat and then used acrylic paint, then the same nail polish as a top coat.  No cracking or pealing.  I have also used sharpies, and acrylic paint pens.  Always using the base / top coat nail poilish before and after. 
I did notice with my DH’s band (gray one), and the only one that I didn’t do a coat of paint first, that his paint did scrape a but from wear and tear.  Mine (purple) and my DD’s didn’t have any problems at all. .Have fun!