There are multiple correct answers for this.

When I've introduced people, I've encouraged/recommended mostly:

1. * Be aware of "set and setting". *

Be with friends (not required), in a familiar and safe environment. I like spontaneity, however, it's best to have certain factors "controlled" for your first experiences. For example, if there's someone that you don't trust, you won't want them around. For similar reasons, it's probably best to avoid the general public. Being in nature will always be better than a populated city/town. I can't stand cars in motion when I'm tripping. Trees are much more fun to deal with.

Have "implements of creativity" at the ready. Musical instruments, paints, paper, writing insteuments, etc. 

TV/movies usually deadens my trips. I don't grok people that trip, then stare at any type of screen for more than a few minutes. Fractal making software blew my mind, so screens aren't something to avoid, but lean toward abstractness, compared to stories with a plot.

2. Set an intention!

This is important whether you're tripping for fun or therapy. Have a clear intention of what you want out of the experience, and state it out loud as you partake. This has tremendous power, so it might be good to define the day beforehand.

3. Enjoy, observe, and learn! 

 Ingest. 

 In my experience, it’s not really worth it. Yes, you may experience your ego being stripped away and be able to see some things differently, but the negative short term side effects were, for me, unpleasant. Better to eat meat, pray, meditate and do daily squats and pushups.