I don't make sloppy joes very often but when i do i always use this recipe. For me once i find something i like sometimes it hard to try new things (if you know what i mean.)
First i took ground beef and added some chopped onions and green pepper and let it cook till the meat wasn't pink anymore.
Then I added:
1/2 tsp garlic powder
1tsp yellow mustard
3 tsp brown sugar
and a little salt and pepper
Stir together and let it simmer 30 minutes
It was delicious.