What kind of bit are you using? I was having the same problems with a mare I had a while back and she only really listened in a bit that had a curb chain.
My advice to you would be to lounge her in the arena before you get on.....it gives her a chance to blow off some steam. I would recommend making eye contact and continue to send her forward until she starts showing that she's calm and submissive (ie chewing, licking, lowering her head).
Once you're done lounging, get on her and ride in the arena at a walk trot canter and back in both directions to warm her up and get you relaxed. Once she's going well and listening to your aids, go ahead and take her to the place you plan to ride.
You have two options at this point, repeat the lounging process outside the arena to show her that its the same as arena work, or you can get on and proceed with your hack.
If she tries to rear or is tense, make her move her feet. This will get her attention back on you and what you want to do.
Hope this helps!
Last edited by luvbear8; 04-25-2011 at 07:46 PM.