If you don't have any hair on the top of your head, you need to do a few things to make sure that your scalp is well taken care of. If you don't, you may wind up with flakey, dry skin.
If you shave your head, make sure you use a conditioning shave balm such as Zia Natural Skincare Hydrashield Shave Cream to avoid any shaving irritation. A triple blade razor like Gillette's Mach3 will help protect against nicks and cuts.Apply sunscreen on a regular basis. Your head is more sensitive to the sun than the rest of your body, and it needs protection. Apply no less than an SPF 15 before you go out in the sun, and don't forget to reapply.
Lastly, moisturize. Your head, just like any other part of your body needs to replenish the moisture that's lost. Use your favorite men's lotion or opt for a fragrance free option like Cetephil Moisturizing Cream.