The best UX I've seen for recycling & composting is putting up a board with examples of each item for each bin. So the aluminum bin would have cans, the commingled bin would have paper, bottles, etc., compost would have a banana peel, compostable forks, etc., and trash would have all the non-recyclable stuff. The only remaining problem is that the examples are non-exhaustive so you still have to guess if the thing you want to throw away isn't up there, but the trash is always safe.