I feel like normal piercings would look good but hed run into the problem of losing them everytime he gets blown up in iceform while in battle. Ice piercings are an economic and original solution.
Dyeing his hair is pretty risky it can look bold or ridiculous depending on what he goes for. I feel like an electric blue to keep with the ice theme would work well.
Tattoos would probably vanish when he recreates his body from moisture. Not to mention artists never remember then cf. Warpath.