Learning lines is an important skill for the actor. You've got to learn your lines before you can step on stage or set and perform. But how do you actually go about it? There are lots of different approaches to the task, and really, you have to find one that suits you. Learning lines is simply about committing the words you have to say to memory - and that's just plain hard work for most people! While some actors have a natural flair for line-learning, others have to spend many hours on the task.
It's important to honour the writer's work, and not paraphrase it. Every time you change the words, even just a little, you change the original meaning that the author intended. While in some contexts "improvisation" around the lines may be permissable, for the most part, the actor is expected to present the words as written. It's your job!
And it's not until after you've learned your lines that a director can really work with you. Some beginning actors think, "As long as I've got my lines down by opening night, I'll be fine..." - but in a professional setting you're usually required to have your lines down early in the project's timeline. Reason being, a director can do far less in creating a scene if you're still wandering around with a script in your hand. You're not free to play, to create, to experiment during the rehearsal process.
And while theatre productions may have long rehearsal processes over many days or weeks, a film project may have very little rehearsal at all. So in that case, you've got no choice - you just have to have those lines in your head ready for the director to call "Action!"
Here are some tips and tricks that may help you get started on learning your lines: