Set and setting! If you're unfamiliar with that term, google it up and do some reading. There is a good deal of information about it, but here's a quick rundown. Set refers to your mind set leading up to and going into the experience. Its good to go into it with a calm, relaxed, open, confident (but respectful!) attitude. None of that "Hurrr, I'ma get fucked up and trip my nuts off!" Although it seems like you're not in that place anyway. Before tripping I'd suggest sorting out any major fears you have about it. If you're really unsure or scared, its not the right time. Get to know your body and mind better and come back to psychedelics at a later date. The most important thing to remember is that its just a drug, its not reality and it wont stay that way forever. If you're taking a reasonable dose of a well used drug, you're more than likely going to come out of it okay. Try coming up with a mantra or happy thought that you can keep tucked away in your head, and focus on it if you start to have trouble during the trip. Even if you have a bad trip, if you accept it and work through it you'll probably come through it okay. Maybe a bit shaken up, but okay. If your trip goes south, don't try to "run" from it, or start into a train of thought where you're like "OH FUCK OH FUCK I'M HAVING A BAD TRIP! SHIIIIIIT!" It doesn't help. But it brings me to the next point...
A trip sitter. Someone who you know and trust who can stay with you (in a sober state) and assist you if you're having a hard time. Somebody who has experience sitting is best, or who at least has experience with such drugs and knows their shit. This can be EXTREMELY helpful, as having someone to talk you back down and to comfort you if you get scared. Or to just help get you things like water and stuff. And if your trip goes phenomenally and you have an earth shattering realization or experience, it can be fantastic to have someone there to help bring you back to reality when you come down. And talking to them about it may help you to integrate such an experience better.
Setting: Simply put, its where you decide to trip. This should be a safe place where you wont have to worry about getting in trouble or where there's danger about. Your house is a good place. If you live with parents, don't do it with them around! Unless they're into that kinda thing. Outdoors can also be good, but make sure that its not an area where you'll have tons of people (cops especially) running across you. And DEFINITELY have a sitter if you're going somewhere remote. Don't wanna get lost in the woods with a head full of mushroom. I suggest your or your sitter's house so that you'll have a safe place to trip out, where you can get water, food, music, etc at your leisure. I would say DON'T do it the first time at a club, a rave, out in the city, etc. Its just not a good idea your first time.
Other ways to help with anxiety and fear. Take time to get ready for the experience. Some suggestions: Clean the space you'll be tripping in, take a nice cleansing shower, light some incense, take some calming and grounding deep breaths, meditate for a while, focus on what you want from the trip (I.E. a mind expanding, exploratory, awaking experience, or whatever your intention is), have a nice cup of tea (green, peppermint, or chamomile are good), listen to some music that puts in you a good headspace, then sit back and enjoy the ride! You don't have to do all that, but they're suggestions.
Permatripping isn't real. You'll come down when the drug wears off, which usually isn't THAT long. You may have a slightly shifted perspective after, but you wont be "tripping." Now, if you abuse the fuck out of psychedelics then you may find yourself in a perpetually...warped state of mind.
Make sure you're WELL educated on the drug you're taking so that you know what to expect as far as side-effects, duration, etc. And lastly, have fun!
Edit: Shit that wasn't a quick rundown at all.