I am a full time caregiver for mentally and physically disabled adults and my best advice is to be patient. When people who are disabled act out and treat you badly, try not to get frustrated. You have to remember that they are disabled and don't see things the way you might.
I have had clients bite me, hit me, spit on me, call me horrible names, just generally make my job really, really hard. You can't get frustrated though, and you most certainly can't get even.
This line of work can be extremely exhausting both mentally and physically. Lifting people taller and bigger than you may be in your job description. You have to remember, no matter how intimidated you may be, they're twice as nervous. Uncomfortable changing an adult diaper on a incontinent client? They're probably embarrassed as hell having someone wiping their butt for them. Lifting someone heavy? Don't tell them they're heavy. Try to act like it's nothing, even though your back and knees are SCREAMING for relief. They already know they depend on other people to live, they don't need to feel bad about their bodies. Trust me, they probably already do.
This job isn't for everyone. But if it's something you are truly interested in, try it out. Make sure you lift with your knees, not your back. Wash your hands ALL THE TIME. Use a watch timer for meds. And be their friend. It makes life easier for both of you. I promise.
Hope this helped!