How to keep your horse calm while saddling?

I have two belgians and the larger of the two (Grace) doesn't like to be saddled. Its not impossible to saddle her or anything but she gets upset when I tighten the cinch and steps over to me. She has gotten quite close to stepping on my feet a couple times. Also she throws her head repeatedly. I'm a beginner when it comes to horses and I was wondering how to correct this behavior. Thanks!