What do you wish you had known before starting up ?
cmos: Stand up for yourself.Don't make any mistakes big enough to kill the company.The moment you realize you can't pay a bill talk to the company you owe money to and explain to them exactly why.  Then offer to work out a payment plan.  You'd be surprised how many companies are just happy your communicating with them and more often than not will work out a payment plan you can handle.If deep inside you are not 100% about a decision or direction, do something about it.  If things don't work out, make sure you won't be able to blame others.Be very cautions about the impact of hiring full time employees.  Once you hire someone who needs healthcare and a 401k your company ceases to be an innocent hobby.