Though most people are well suited for a navel piercing, there is one major exception: if the point your torso creases at runs through the navel (or close enough to put pressure on your jewelry when you bend over) you should NOT use a ring and in fact will probably be best off NOT getting this piercing at all. 
The ideal belly button would have extra skin or folds in the area that you want pierced. The better the fold is above the belly button, the more likely your body is to treat it as two separate wounds, rather than one wound with something stuck in it that needs to be rejected.
Bottom Belly Button Piercing

Although belly button piercings are normally done on the top fold of the belly button, inverse navel piercings allow you to wear jewelry on the bottom of your belly button, too! Compared to top belly button piercing, you need to exercise even more caution during the healing process. Bottom belly button piercings take much longer to heal and they are in an area you are likely to move and stretch during daily activities.