1. Writing down your lines will work the best.
2. Try practicing with the blocking. I found I remember the script better when my body is doing the actions of the play.
3. Also, making a conscious point of remembering what your character wants in each scene. Once you know why he or she is in the scene, then the lines flow better because what is going on in the scene makes more sense.
4. I've done plays too where the other actors would be jumpy with their lines; the best way to practice for this problem is to write your que lines on index cards, and write your response-lines on the back. Shuffle them by scene if you like.
However, seeing that it is "BEAUTY and the BEAST" a lot of your lines will be to music so this will help with the memorization. Most importantly though is just to remember to HAVE FUN with the character and nurture her. Be nice to chorus cast because they will save your butt if you're good to them. Give love to the techies too, the production would not happen without them! =)
!!!SIDE TIP THAT I PROMISE WILL HELP YOU OUT A LOT AS IT HAS ME SO MUCH!!!
When going over your lines to yourself; never practice it with specific inflections that you've been doing onstage. This is crucial because what happens when you practice inflections consistently, the natural feel of the scene/dialogue is lost. Reviewing the script like this will make it where your character's lines no longer feels like lines and start to feel like actual responses/reacting to what is being said/done on stage...meaning it will start to look and sound real because your voice infections will be really in response of the others' dialogue as opposed to sounding like the dialogue in porn movies...if that makes sense.