The absolute best resource in my opinion is Brian O'Neil's book Acting As A Business: Strategies For Success. It gives different examples of the correct acting resume format.
Keep it short. The acting resume format is one page only that fits on the back of your headshot. If you have a lot of credits, you can adjust the font size and/or write down only your most impressive roles.
The Beginner Acting Resume Format, And Beyond..
The acting resume format is very specific and has to be followed by the letter if you want to get calls for professional acting auditions. Start by looking at the acting resume samples on this page to get the big picture, then read about the details of writing your resume below, along with do's and don'ts and how to make your actor resume stand out.