Well, there's a lot to be said for a first psych experience being DMT. It will be INTENSE, but that will always remain so even if you've done thumbprints of LSD. Yet it will prime you for many experiences to come (if psychedelics are for you), and it's not dangerous or anything. It's short acting, yes, though it might not feel that way. I think you just have to question yourself if you want to have your socks rocked off, but don't let the intensity scare you off. I would start low, like 20mgs or something, just to get a taster. Then go for the real deal. If you want to.
Otherwise, if you want to start out a bit more conservative (doesn't make you a pussy though!), just make sure you have a quiet place out in nature where it's safe for you and your friend to hang out for a few hours. The substance doesn't nearly matter as much if the set/setting is correct. Just plan out ahead, and make sure you have all the right things with you (music, drinks, maybe a bit of food) Don't go for too much of a dose, but too low isn't really fun either and might make you anxious. Just ask the dealer-person what he'd think would be a right dose for a first timer, he knows his hits well, even if the validity of his information might seem questionable. You might want to abstain from smoking weed, as it raises anxiety, but if it feels right then why not? Also, be sure to just research everything about the substance you end up taking.
If you get LSD, it might be wise to get an Ehrlich testing kit to verify the substance.