I totally started putting the conventional way and i'm a right handed putter. So my left hand was always up and my right hand was down. I would overlap my fingers so i could get a food feel of the putter. I would always come up short or long and couldn't figure out the best way to fix this problem. So i started putting my left hand low and couldn't believe how this changed my life. I am now putting the ball more consistently and also making more putts then ever before. This is also dropping about 5+ shots off my game and lowering my average score.  

I put right hand low being a lefty so I putt cross handed and it has definitely improved my putting.  I think it gives the stroke a more natural looking arc.

I'm right handed and I have the normal grip, except I put my right index finger down the side of the grip. Thinking about changing though. 

You could even try an oversized grip.  Takes a bit to get use to but in the long run really helped my game. 

I use a reverse overlap, and a mid size grip. I started with the mid size this winter, and I love it. It takes the sloppiness out of your hands and wrists without having a death grip on the club. It really makes putting easier.

I like using a conventional grip sometimes putting my index finger down the shaft. Ive tried the claw and crosshanded but i dont like it, it feels awkward.