A solid buyer's contract. You'll want to be able to terminate the buy agreement if you are unable to flip the contract or complete the purchase. The ability to pull the title history. You certainly don't want to purchase a home that does not have a marketable title chain. An assignment contract. If you want to assign the contract to rather than handle the remodel, you'll need a contract to protect your right to get paid on the assignment. Contracts for trades. You want to be able to incentivize early completion and prevent overruns on costs. To name a few.