You can get her used to grooming, touching every part of her body, the clippers and picking up all four feet on command. Teach her to stack properly, if you plan to show her in halter and to walk and trot properly at your side. Also get her used to being around loud noises, in case you wish to enter parades later. Make a trail course and start her in that. I don't suggest trick training any horse though, until they have the basics down thoroughly.
Do be careful lunging a Mini though. Many can get a rear leg 'locked'. This seems to be more seen in Minis, than other breeds.