Write. Them. Out. Seriously. It's tedious and a pain in the ass, but it will help you more than you realize. I also break it down by scene. Learn a whole scene at a time. Every time you mess up, start over. For both lines and lyrics, repetition is key. Listen to your songs over and over and over until your ears bleed. Write the lyrics out if you find that it's helping you with your lines. Also, I highly suggest you invest in one of these: http://www.amazon.com/Actions-Actors-Thesaurus-Marina-Caldarone/dp/0896762521 Put an action word with every line in your script and memorize the word along with the line. Actors need actions, and the word you've chosen should help trigger your memory for what the line is. Hope that helps! Break a leg!