1. Hire for what you need now, try not to overhire for too many future ideas. You just burn cash and it hurts the business.
2. In the early stages hire more for culture than just pure raw talent. If you have a person who is a 10/10 technically but a 7/10 culture, but you have a 10/10 culture and 7/10 technical, take the culture fit first. You need people who can be flexible and work with the team more than one person who happens to be an amazing engineer or whatever.
3. Look for people who share an understanding about startups. Meaning they won't feel demeaned if you ask them to clean up the bathroom before an important client/investor visit. I always had this as a standing rule in my teams, I'll be the first to take the worst job, but everyone has to help do it in the early days. If they get this, they are a team player, if they are too good for it, pass on them. I can't stress this enough in the early days. Later on, not so critical but I always will favor #2 and #3 people.
4. Try to hire specialized generalists in the beginning whenever possible. Sounds like an oxymoron but it isn't. You want someone who is say deep in one area but is capable of helping across the spectrum and is happy to do it. Kinda goes with #3.
5. When hiring business people, always always always hire culture. They are the face and voice to the client, if they don't share the values of the team you are done from the start.
6. Don't get hung up on where someone went to school or what degree they do or don't have. Look at the people applying, treat them with respect and your companies name will spread quickly. If everyone who interviews with you walks away and says damn, I didn't get that job but man I sure would like to work with them, you've done excellent.
7. Focus on treating people right and doing what is right more than what is easy or expedient. We use the value of "people first" where I am at now, and it is a value I take to every environment I lead in. Does that mean we have never screwed up and upset someone, NO. Does it mean we have always done our best to put the person over the easier options, yea, we have tried.
8. Don't disrespect engineers and give them a "test" to do at home and send to you. This is a major red flag to me for any employer, but it is not uncommon in SV. If you want to test them, respect their time and yours and talk to them. You want to test their ability to read code and deal with it, show them code and have them talk to you about it and what it does/doesn't do and what is wrong/right with it. Along with this one, don't do meaningless whiteboard problems asking them to reverse a string, who cares. Ask real questions.
9. Asking real questions in interviews is important. There is a trend right now in SV where they like to separate "culture fit" interviews from "Engineering" interviews. This is crap. Doing them separately is a waste of time and isn't realistic. Combine them into a conversation, sit with your candidates (phone, in person whatever) and talk with them like they are a team member, ask them hard questions, find out what they know and don't know, but do it as a team member and you'll learn all you need to know about their culture fit and technical skills and save multiple rounds of interviews. This also means you'll get to candidates while other startups are wasting time scheduling more and more rounds. Early on, if there are two of you founding the company, there should be at max two rounds besides an initial phone screen. If there are 3 or more, you need to make it two-three rounds max, and make all hiring decisions in say 7-10 days at max. Don't do the wait and see if something better comes along, you'll lose time waiting, if you find a good fit they are a good fit.
Ok I could write a book, sorry, bit of a passion thing for me on hiring. Always happy to share experiences and answer questions I can, 20+ years of building teams has let me make a lot of mistakes to learn from.