[Serious] People who started up their own company what are the the Do's and Don't's that you wish you knew before you made your start up?

Source.

Do's
Research lots and lots of research.
Swallow or eliminate all fear ( fear can have one over thinking and sabotage oneself.
Push away anyone who tells you you can't or it won't work because they tried and failed.
You could also push ahead ignore them and use them as motivation to succeed.
Start small and grow millionaires aren't made over night unless you win it or steal it.
Keep an open mind and return to first on the list research research research with any business there is always room for improvement.
Marketing always let as many know about your business as possible.
Build a good reputation be respectful rudeness may seem to work in some businesses ( good customer service needs to make a comeback) a happy customer is a returning customer.
Don't s are the exact opposite of said in do 's