Going to go to first yoga retreat

I've decided to go to a yoga and meditation retreat - it will be over a weekend, starting on Fri night and ending on Sunday afternoon. I've never been to one before and was wondering how I should go about selecting one. Are there certain things I should look for in the offerings? Any tips and advice from anyone who has been to one would be helpful - things they liked, things they didn't like..Does the number of other people there make a difference?

Thanks