A putter can be heel shafted or face balanced. A heel-shafted putter has a hosel at the rearward part of the putter head. If a putter is face balanced, its face will be parallel to the ground when the shaft is balanced on your finger. Ben Crenshaw and Phil Mickleson putt in this manner. A player with a straight back and through stroke will benefit from a face balanced putter.
Face balanced putters encourage the player to move the putter directly up and down the target line.
Next take a look at how true your ball rolls on the green as you putt. If the ball bounces, this could be an indication that the loft of the putter does not match your stroke. Loft is designed to assist in getting the ball rolling on top of the grass as quickly as possible. As far as loft is concerned, most putters have between 2 and 6 degrees of loft. If you forward press your hands a great deal, then a putter with more measured loft might be a good choice.