You have a putt that is about 6 feet long, dead straight and on as good a putting surface as you can have. The requirement from your putting technique is only to be able to strike the ball with enough energy to reach somewhere between the hole and approximately 12 inches past the location of the hole, and of course to return the clubface square on to the straight target line when striking the ball. Assuming there are no unfortunate bobbles or strong gusts of winds, the effect will be determined by the above impact factors. The result of the putt will not be a direct result of alignment at address or ball position or width of stance or grip etc. All of these things can be compensated for during the stroke. So the point I want to make here is that no amount of efficiency in our technique will make up for lack of effectiveness. But before you think I am advocating doing just anything I would like to make a case for looking at the efficiency of our putting set up and how with a bit of practice and repetition we can optimize our chances of becoming very effective at holing putts.
One of the really simple points here is to be able to hit the putt on our intended start line, efficiency would strongly suggest pointing the clubface in this direction at the address position to begin with. This is obviously something that most if not all us are intending to do but unfortunately a large number of club golfers do not do it as well as they think (this regrettably includes myself). The first thing I would suggest is that you check your clubface alignment at address. You may need another person to help you check this by standing behind the line of a straight 6 foot putt on the putting green and then telling you where you are pointing the putter face at address. This alignment and correction can also be done very effectively with a simple builders chalk line being used on the putting green. In general terms if you have a miss alignment when first using a chalk line it will either look wrong to you at address or you will consistently miss the putt to one side, giving an indication of the compensation that has been happening in the existing technique.
If you have found some miss alignment you should also consider your ball position (front to back). If you have a tendency to aim left try moving the ball back in your stance a little and of course vice versa. It doesn’t need to be radical I’m only suggesting about a 1 inch or so change. Another thing to consider is the ball position in relation to how far you stand from the ball. If you have a habit during the stroke of bringing the putter too much on the inside it may be worth altering and standing a little closer to the ball, once again this does not have to be a big alteration. Equally the opposite can apply if have a stroke that in particular lifts the putter away, outside the line in the take away.
One of the things I am a big fan of at address and during the putting stroke is that the shaft of the putter is an extension of the forearm arm angle. In efficiency terms this helps put in solid foundations to delivering a consistent clubface.