I have several favorite warm-ups which can be easily altered and adjusted to your needs. I name them in random order because they are all good.
1. Guess who I am. You need a card for each student. The cards can be with the names of professions, hobbies, crimes, anything you can create or imagine. The procedure is quite simple. You give out all the cards, students can explain their card or even mime one by one. The rest of the group should guess it. I love to do it especially with new groups. Advantage: everyone is practicing speaking and everyone is listening carefully in order to guess.