ASK HN: How should I set my company up? 
qhoxie: To my knowledge, there is no perfect way of transferring a merchant account.  Your best bet is the advice Ryan offered:  choose the biggest, most prevalent merchant account provider you canAlso, this is not particular to tech or startups, but keeping solid documents will make any sale much smoother.  Use something like gnucash, mint/wesabe, quickbooks, etc.If by company you mean incorporation, I believe that Delaware LLCs are generally considered the best option.