Be prepared to be asked unrealistic things with no support,
PMs who will either:
never appreciate your effort, take credit for your accomplishments, make promises with no intention of keeping them, work you 90/hrs then question your overtime, gossip, and worst of all have absolutely no competence in the field in which there project is.
I believed what I was told, worked hard while making 1/8 of the others around me for revampingentire systems, and then wasn't even issued a reason for termination when my contract through staffing was over.
If you value yourself, don't work for these people. They will not reward your effort, or what you've done for them.