Don't eat power pellets unless you need them. They're precious resources, and you want to gobble them down when they can do the most good, just like in conventional Pac-Man games. When you do eat one, your enemies will temporarily become vulnerable, until the effects expire. You can eat a second pellet--or extend an activated power-up, when appropriate--to keep a combo going, so try to string together combos for more points. Just don't get greedy.