Search this board. It's been discussed a few times.
You have to get a tax sticker (varies by state) for each machine. You'll need contracts. You'll need liability insurance (what if your machine causes a fire? What if it didn't cause it but the location owner SAYS it did?) Splits are usually 50/50. You'll have to agree on the accounting practices (likely will need a coin sorter that you can bring with you on site). If the place already has vending machines, or anything else like that, and you still somehow manage to get your machine in there, expect the other operators to be "unkind" to your machine. (Though most of them have contracts preventing outsiders like you from placing equipment in the first place).
If you want to save yourself the trouble, take a wad of cash and burn it.
