my short game is always what saves my game from my inconsistant ball striking. my grandfather's quote has always resonated loudly, "no sense in hitting it close if you miss the putt".
With all that said, I would say i'm an above average putter (maybe not the most consistant) but in general I'll have the lowest putt totals in my group. The main reason is practice. I am up at the putting green, chipping as well, for at least an hour 6 out of 7 days a week in the summer. That is the most simplistic way to achieve better putting.
As far as technique it is tough to lend advice in an age of 1000s of different putter heads, lengths, styles, and those icky belly putters. What I would advise is focus on getting the ball rolling immediately and end over end. That is the formula to consistant putting and gives your ball the best chance of dropping. A common mistake is focussing on having your hands foward and ahead of the ball. It isn't necesarily a bad thing but it can interupt the pendulum motion and make you actually raise your hands/elbows in the back stroke and follow through, i.e. no dice. What you want is a slight opening and closing of the club head and almost hitting the ball with an upswing to promote the ball rolling right off the bat as opposed to it skidding along for the first few feet of the roll.
My last comment is a quick story: On my golf team in high school we had an outside instructor come in to help for a week. He was working on putting one day and said, "did you know that every putt actually skids for the first 30% of its total distance?" and me and my friend snapped our necks at each other because we knew this was simply not true and ESPECIALLY not true of good putters. I had to interject and ask him to mentally review what we've all seen at this point and that is close ups of Tiger Woods' putts and how his ball instantly rolls end over end right off the blade. One easy to find video is his famous putt on 18 from the Sunday round of the 2008 Torrey Pines US Open.