Here is a Weird Trick to learn lines.
This is the method I use.
Record! Get out your voice recording app on your trusty smartphone and record the other persons lines one by one. Then on play back you say your lines in between.
If you have a big chunk of dialogue record all of your lines as a song or a rap. Seriously this works! Playback with Earphones and dance to it! It works fast!
Take note of the words you keep forgetting. These are what I call transitions words. Write these down In all Caps and Draw a picture next to them.
Flash cards. If you have a lot of banter back-and-forth one-liners this is a great method. Write the cue line on one side and your lines on the other side.
Quiz yo self.
Print lyrics. Learn the story of each verse chorus and bridge. Draw a picture clue and write one keyword to represent each section. For example in the song “Here comes the sun” draw a sun and write “Here”
look at your notes and see if you can do one verse just from your notes.
Take note of the same words you keep forgetting and write them in Capitals.
Repeat with the rest of song sections.
If the song is repetitive write a number next to each section that repeats.