This is an interesting question, and the answer depends upon a lot of factors. Being in business with friends can either be the best thing you ever did, or the worst nightmare (and friend-destroyer) ever.
A lot of this depends upon you and your friend’s personalities, and the way that each of you approaches business. Being in business with anyone is going to be very stressful at times. How do you resolve disagreements (and there will be many), how do you each divide the work (and there will be inequalities), and how do you each manage (management styles can be a lot different than friendship styles). In a casual friendship, lots of stuff that might otherwise cause friction and conflict gets avoided. Take that same pair and put them in a business environment and you may have a giant cat fight.
I have been in partnership with “friends” and it ended badly. It turns out my friend was very insecure, and from a large corporate environment. He needed to play politics, create factions, and act like he was back in Corporate America. It’s the only way he knew how to act. I’m a small company guy. Politics, factions, rumors, “back channel” stuff and the like drives me bats. Say what you mean, everyone work on the same team, and if you have a beef, speak up. He left after less than a year, very frustrated. End of that friendship.
So, my suggestion is to keep friendship and business separate. Unless you really can’t make it on your own, then consider hiring someone, but not a friend. Somebody has to be in charge. Group decision making is fine in theory, but almost impossible to make work in the real world. Partnerships are difficult and dangerous, and they always lead to feelings of entitlement and conflict. Better to have a clear chart of organization. One person is the boss. The rare partnerships that tend to work out have this sort of clear military hierarchy