Play more break than you think necessary, playing too little break makes for longer second putts because every rotation of the ball past the hole is moving away from the hole and makes your next putt longer
Keep you putting simple by developing an easy one-two count, take your backswing on the one count and the your through swing on the two count and create a constant pace to your putts
Slices occur only because your clubface is open at impact, there are several reasons why this must happen but your object should be to assure that the back of your left hand is square to the target at impact