What types of waste should I avoid putting into my compost heap?

DEFINITELY stay away from meats, fats, and grains (such as pasta, bread, etc.). Add any peels (potato, cucumber, carrot, etc.), rinds (melons), leftover salad greens, lawn clippings, leaves, etc. Toss larger chunks of fruits sparingly (they can really stink up the pile) and stay away from citrus. We've tossed tomatoes & grapes without any bad result...once it's broken down the pH neutralizes somewhat anyways. Chop larger pieces up to speed up the compost process and be sure you turn the pile fairly often & keep it moist.

It sounds like you're doing better than most people already! I have a friend with a fairly large block (2 acres) and she is always on the lookout for organic matter - seaweed (don't suppose there's much of that in the Ozarks?), if she sees someone mowing a park or pruning trees she's straight over there with her trailer to collect the trimmings, she has a mulching machine and chops it up and composts it. I have nowhere near enough room to do that much, but I do get some seaweed occasionally and do a bit of mulching of tree prunings I come across.

Do not put anything in that is not vegetation or produce related. That simple.

Soil or soil amendments are the exception.