What is your experience in selling common stock (for a bit of founder liquidity) during an investment round?

Anything before the Series B is heavily frowned upon while Series C is more of the norm. You can negotiate the ability to sell up to 10% of your equity without a board investor approval in financing.

I received a term sheet from an investor! What do I do now?
In your experience, are pro rata rights common in a Note at our stage? If not, do you have any advice about how to respond to social starts?
We received a pre-emptive term sheet for a Series B of a raise of around $25m at around a $90m Pre. The lead VC has asked for Veto Rights to block an acquisition if the company would get less than 2x a return on their investment in that acquisition.
Our current stock option pool is @ 10%, distributed as I see fit. At Seed, it was fully distributed--but now, I want to use 3% for key hires and 7% for myself. However, a board member thinks founder top-up only occurs after Series A. Does this make sense?
Deciding whether to pursue founder friendly preferred stock