Some good tips posted so all I am going to say it that you should keep it simple and that colour washes are the place to start.
A lot of people get caught up in trying to do a "wow factor" show when they first start out. I know that I did and it bit
me! Simple colour changes are nice and effective and will provide a great basis on which to build
One think that I would strongly recommend is to talk to the performers and add notes to their set list
. For example, which songs are slow, fast, happy, sad etc
. This will help you pic which of your colours you will predominately use for that song.
Hope this helps.