Bring a sheet of paper, stickers and a bag of small items like pencils, toys, and pens. When they do something good, give them a sticker. When they get 5 stickers, let them choose some thing from the prize bag.
Bring Things To Do
Bring a stuffed animal, some books, some crayons, an activity book, and maybe a movie. This way, you'll never run out of things to do!
Keep Away Monsters
What I do to keep away "monsters" is bring my hair spray that smells like apples, covered I paper that says "monster go away spray" I tell them that mosters hate apples, so when they smell this, they leave. I add 2 sprays under their bed, 2 sprays in their closet, and a spray on their pillow.
Make Deals
Lets say that the little boy you're babysitting refuses to get ready for bed. If you decide to do idea # 1 tell them that if he gets ready for bed, he'll get a sticker. If you decide not to, tell him that if hhe doesn't get ready for bed, you won't be able to read him a story.
Clean Up
If you have more than one kid, and the house is dirty, have each kid have a turn being the queen or king of each room. The other kid(s) will be their "servants." the king/queen will tell the servants what to clean, and they have to clean it.
Have a "Baby Sitting Bear"
bring a small stuffed animal with you when you babysit. Tell the kid(s) that it is your baby sitting bear (or whatever type of animal it is) and that they help you out. Tell the kid(s) that they know everything you need to know when babysitting, like what to do in emergencies. Trust me, they'll love it!