What will make it easier for me to memorize lines?
I think the best and easiest way to learn lines is working on the acting and actually not worrying about the lines. The more you rehearse, the more your lines will come naturally to you, until you realize you’re hardly looking down at the words anymore. Just keep the text in your hand as you work on your objectives and connecting to your partner in a scene. It doesn’t matter what acting method you use. As an actor, you should always know why you’re speaking a particular line of dialogue. Actually, if you have trouble learning some lines, it could be a very helpful clue to something you haven’t figured out in your scene or monologue yet, so take extra time with the lines you’re having problems memorizing and examine what drives your character to say those lines. Work on your scene and monologue until you know exactly why you’re saying every line and the lines will come easily.
When you don’t have an acting partner to work with, spend some time on script analysis, figuring out the subtext of your monologue or scene. I find reading your lines out loud is helpful when you’re doing that, because it’s easier to commit them to memory when you hear them.
If you’re not familiar with Stella Adler, you may want to read about her technique. Her exercises to experience the lines actually help learning them.
Also check out my answer to this question about learning lines. It offers other acting tips on memorizing lines. I talk about this soap actor who could memorize lines in minutes, which shows that learning lines becomes easier the more we do it!