[Long Post] Preteen question advice needed: being low-key to avoid being picked on?

So. The thing is this. I have an 11 year old preteen daughter. And of course, I'm very biased, as she is my daughter. But she is really sweet in an innocent kinda way, has tons of friends, and is very, very popular. Not in a bitchy teen kinda way, but in a 'I don't care about makeup, and simply hang out and play soccer and videogames with ALL the girls and boys of my age at school' kinda way.

But, she has been somewhat picked on by bullies. Particularily when approaching/befriending girls who are part of girl groups with dominant alpha queens. This has happened twice. The alpha queen little bitches of those groups have then been threatened by her, and have been mean to her. Like spreading rumours, and punishing the girls that want to hang out with her by pushing those girls out of the group, thus freezing/pushing her out.

Now she is just about to begin sixth grade in a new school, and I know for a fact that several girls that have been part of those groups will be there, and know each other since before. So there is a chance that this ugly situation will rear it's ugly head again.

So I'm looking for advice here. Is there any strategy I could somehow pass on to my daughter to make her avoid that trap? Like being low-key at the beginning when being introduced to a new group, something like that? The issue is further complicated by the fact that she is only 11 years old. So I need some simple strategy that she can understand/grasp, and that doesen't seem to manipulative.