Julie Zhuo, on Medium:

[Start-ups] need people who:

operate with good intuition. There’s simply not enough time, money, or people at a start-up to invest in a bunch of research or data-gathering. Good product and people intuitions are what lead to successful outcomes in the arena of high-risk plays.

are well-rounded, jack-of-all-trades. It’s more important to have something be functional and done quickly than it is to be done in the most scalable and robust way. That’s why people who can jump into any number of problems and Mcgyver it are so highly valued at start-ups. Practicality matters; specialists and sticklers for perfection need not apply.

are proactive and don’t mind ambiguity. If you’re looking for someone to give you mentorship, training, or a structured environment in which to learn and grow, working at a start-up is going to be frustrating because those are not going to be priorities for the company.

possess a healthy dose of optimism. You have to believe what you’re doing is valuable in order for it to actually be valuable. If you don’t feel that optimism but find yourself attracted to the idea of a start-up for other reasons fortune or fame or freedom there are other, more certain routes to achieve those goals.

Spot on. All of these also apply for building a start-up team within an established company.

Also, “big” companies aren’t all that bad. There are trade-offs for sure, but no company is completely perfect or terrible, regardless of size.