I definitely make most of mine by posting (and I've probably spent about a thousand TBTs by now, maybe more). Hybrid shops and villager trading seem to be some of the good ways of making TBTs.
Do you have a specific goal in mind that you're trying to reach?
You can make them by posting a lot, though that requires you to be on here a lot obviously lol. You can also sell in game stuff like furniture, clothes, hybrids, etc. I've also gotten tbt from selling a few villagers that I didn't want in my town, I sell my own hybrids, items (gardening stuff like saplings, bushes) and I also sell pokemon which has gotten me a good amount.
Like everyone has said, posting is probably the easiest way to earn them. Probably not the fastest, but it's the easiest. Unless you bother to open a shop where you sell stuff, deoending on what you're selling you can get rich quick. I've never made a shop that's why I'm so poor. I don't draw or make art either so...
