What is the best way to run your startup before incorporation? For example if I were getting a startup ready for Y combinator and you recommend not incorporating beforehand, how do you recommend handling any business transactions that would occur in the meantime?
DBA or LLC. Costs $20 or $200, respectively, and each takes about an afternoon to fill out the forms and file. Or just do business as an individual. If you don't need a business bank account, you can do that too. PayPal and Google checkout will accept money on your behalf without much trouble.