When players start missing short putts, they immediately blame their stroke when, in fact, the fault may be allowing for too much break. A putt of three feet or less usually doesn't have enough time to break more than a couple of inches before reaching the hole. If most of your short putts are sliding by on the high side of the cup -- indicating that they haven't had time to break -- then this is likely your problem. Therefore, don't aim short putts anywhere outside the edges of the cup.
A good idea is to simplify things by breaking the cup down into five parts -- left edge, left center, center, right center and right edge -- giving you five possible places to aim, all within the cup.
There are two situations when you'll have to ignore the preceding advice and aim outside the hole:
1. Very sharp slope on an extremely fast green
2. Sharp slope on Bermuda grass, but only when the grain and slope run in the same direction.
In all other situations, your best bet is not to give the hole away on short putts.