My two cents is: you get five points for pairing with a friend, because of the advantages that brings. However, the points you will theoretically LOSE for going in on a project with a friend ranges from 0 to 6. I for example got deeply involved with a friend (well, a good acquaintance) and didn't do all the DD I probably should have (taking stuff on faith). Fast forward to today: it has been 20 months instead of 9, and I'm $45,000 over budget (I'm the capital partner). I have stayed awake at night and gotten a few grey hairs.
If you want to get involved with a friend, try to limit your downside by saying Hey I like you and trust you but we have to go about this as though we are not friends, but strangers. Take nothing on faith. If it works out, that's great -- and from what we know of each other, it may very well. But we need to proceed as though it will fail, and thus do a lot of DD, trust but verify, and put everything in writing.
Feelings can get hurt with friends in a way that is not likely with strangers.
Having said all this, I have a deal with a friend that has been going on for 3 years and there are no hiccups to speak of. Now, I didn't do a hell of a lot of DD, so it's almost lucky that things are still peachy.
If you have a good idea and/or skills and/or financial capacity, you might very well be able to find a non-friend to do a project with.
Man, there are so many bumps and bruises one has to endure on their way up the ladder. I don't envy you! When you see someone who has been active and fairly successful over a 5+ year period, or someone who has 1,000 or 2,000 posts on BP, they merit your respect (all things being equal) because this business can chew up and spit newbies out. That's not to scare you exactly, but to say you have to be very careful. Take off rose-colored glasses and be prepared to take some lumps.
WIshing you the best, of course :)