Someone can hold your Horse or give him a snack ;)
Have some one help you get on by holding her still and if she stands rewards her for it and make her stand before you move
If you are looking to fix the root of the problem, the do ground work, gain her respect first, and do the step by step way like put only one foot in until she doesn't move, then lean your weight on the saddle, and stuff like that. But if you just want to get on regardless, hold your right rein tighter since you mount on the left side and horse's red to move away from pressure so she will most likely stay. Anticipate what she's going to do, since the horses I've ridden who had that problem always move their hind quarters away. Try to get up quickly before she can move.
When I have my pony racked up to ride and I lift up her rains to get up she always moves away from me and I’ve tried to hold her mane too and she keeps moving, even when someone’s holding her she still tries to move away and when she didn’t have any tack in her I just held her main and she moved away from me (and I wasn’t even pulling her main I just held it ) is there something I can do?