as an intern the enthusiasm to work hard on the most mundane and dull tasks will put you in a good stead. Having been a first year grad on several different teams and then a second year on the same teams with an underling below me heres a few good/bad things you can do:
Be happy to help on pretty much anything, no matter how ****/mundane the work seems, 99% of the time you're being asked to do it for a reason.
Get along with everyone on the team. Even if you're working with a complete jerk, get on with them, looks very good from a managers persective if they know that xyz is hard to work with.
Be willing to speak up but don't be overbearing/arrogant or ever try to force your ideas on to someone
Do an inordinate amount of tea/coffee runs
Don't grumble about tasks/hours/work etc
Don't sit there saying nothing
And the one I find most annoying is when I ask someone to do something and they reply that they are busy despite the fact I've got about 10x more on my plate than they have.