I try to memorize 4 algorithms a week. Just do it again and again while thinking about the case that it solves for. Try to do it without looking at the algorithm. Otherwise, just practice.
Make sure to review algs you have already learned so you don't forget them.
4-look means using four algorithms to accomplish the given task. For example, a 4-look OLL would require four algorithms to be executed on the cube to orient the last layer.