Make a long, lazy, slow-paced swing to create a high trajectory. This gets the ball up high so that it lands softly and does not roll. It is a risky shot, so only play it once you have practiced it sufficiently.
Most thin or topped shots are not caused by picking your head up, as commonly believed, but rather because your muscles tense up and shorten the distance from your club to the ground
When just off the green you can either putt through the fringe or chip using one of these two chipping techniques, don't just do one, try all three and use the one that you are most comfortable with