What do you wish you were told before you started freelancing?

[Btaliat]

Not as a regret only. But sometimes assuming we know better, we may do better. There are some information that you were not told in freelancing and surely lack of these information really hunt you badly. Whether you wouldn't have ventured into freelancing or you would have done better than the stage that you are, you are just regretting not being told such a crucial information. Which information is that? Can you share it in the comment section for others to learn from it.