Groups can be most creative if they are comfortable with each other. Creativity requires reduction of inhibitions and the willingness to make mistakes: In short, fearlessness.
To that end, some kind of ice-breaker would be useful. Here are some examples and I think the original lists are available from these links:
Giants, wizards and elves. This is probably better for children and quite active.
Unique and Shared. More sedate.
Alphabet Soup. More ESL-related
Draw Your Name. Pictures and ESL