I've lived through several mergers/acquisitions and consulted with start-ups on strategy at the same phase you are in. In one acquisition, a company bought ours for cash, I made it through the integration period (with all my money), went on to start another company but then watched from the sidelines as the new owners decimate what was once a high-powered team. They bought at $775 million then sold 5 years later at $25 million.
So, here are 3 concurrent concerns to watch out for:
1) Be clear why you want to sell your start-up. Are you looking to exit/pass it on to cash out or do you see a buyer as helping you fulfill your vision with resources and money?
2) People, people, people. Leadership, leadership, leadership. If you view your start-up as a going concern, you have to look at your people and the buyer's leadership and people. I've seen many acquisitions crumble after the sale because of the wrong mix of people and leadership. This will haunt you and then hurt you if you have any kind of post-acquisition contingent payment hanging over your head and torture you if the buyer pays you to stick around.
3) What's in it for your start-up team? This again depends on your intent. My assumption is that the buyer would be buying your team along with your product, service and/or IP so keeping your team committed would be part of the deal.
I can talk you through those concerns, share my experience, and help you think about your next move. A 30-minute call should be enough to start.