Babak Nivi Co-Founder AngelList and Venture Hacks and angel investor
Nivi says “the biggest mistake entrepreneurs make when  raising money” is that “[they] focus on valuation when they should be focusing on controlling the company through board control and limited protective provisions. (Protective provisions let preferred shareholders veto certain actions, such as selling the company or raising capital.)
Valuation is temporary, control is forever. For example, the valuation of [a] company is irrelevant if the board terminates [the founder] and [he] [loses his] unvested stock.
The easiest way to maintain control of a startup is to create good alternatives while  raising money. If [the founder is] not willing to walk away from a deal, [he] won’t get a good deal. Great alternatives make it easy to walk away.
Create alternatives by focusing on fund-raising: pitch and negotiate with all  prospective investors at once. This may seem obvious but entrepreneurs often meet investors one-after-another, instead of all-at-once.
Focusing on fund-raising creates the scarcity and social proof that close deals. Focus also yields a quick yes or no from investors so entrepreneurs can avoid perpetually raising capital.” Babak Nivi, What’s the biggest mistake entrepreneurs make? , October 14th, 2007 http://venturehacks.com/articles/biggest-mistake; Why do investors want protective provisions? August 2nd, 2007; http://venturehacks.com/articles/understand-protective-provisions