The most important thing is going in with the right mindset.  

The way you described Bria coincides heavily with a friend of my own who has had multiple great trips. For the first few times try to plan out a trip in the safety of someone's home for the most intense parts (others may tell you to spend it in nature, which I do not disagree with one bit. Just be sure that it's an area that you are familiar with). If you guys are doing a single dose, you'll probably want to have at least 6 hours planned out (with no driving involved).

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  Now going in with the right mindset is not too difficult. I would describe it as feeling like a kid again. Every sense seems to pick up more wonder than before. Music is different; it makes you feel. Things become funnier and you get crazy giggles. The come-up phase can only be described as intense, as you may get that feeling that you're a slice of butter meltin' on a big ol' pile of FLAPJACKS.  

Once you peak and are starting the falling action of your trip, however, there generally seems to be a phase where you just think really hard. It's a period where you really start pondering and looking at situations in ways that you may have never considered before. Things like empathy become extremely prevalent and certain opinions of others that you may not have agreed with will begin to show their logic; you'll begin to understand the frame of mind of the other people. You begin to notice subtle things in body language during conversations. I recommend one-on-one conversations when tripping because the dynamic changes so much when you add even one other person to the conversation.

  Sometimes the smallest event will just feel so dramatic because you'll be considering several ramifications of said event, no matter how insignificant. So long as you're with people who are generally sensible and will keep you on the right track, this portion of the trip is where--I feel--people can experience the most growth.

  Sobering, but necessary, topics are bound to come up. Just be sure that if they're grounded in reality and not just illusions of self-consciousness, that you find a silver lining in them. It's what everyone needs.  

  From what I know about your situation and from what I have encountered myself, I would say that this could be an extremely clarifying experience for you two.