Whenever I memorize algorithms, I pick one, and do it over and over watching the algorithm. Then I try to do the move without the paper. Do that over and over about 50 times, and don't try to do more than one algorithm a day.
After studying the Fridrich for long enough you start to recognize that some of the OLL and PLL algorithms are the same as or close to the F2L. Also you may recognize many algorithms as being the opposite or mirrored. This helps shrink down the number of formulas you will need to memorize.