I know this has been discussed before but I'm asking any experienced psychonaut to chime in. I want to discuss the general and the specifics of getting the most out of your experience and being as comfortable as you can in hyperspace. Things to do, things to not do.
For me, if I have something on my mind, I will not smoke DMT that day. Weird things have sent me into a panic like state under the influence. I'm talking about a recent lie I just said. I didn't realize a lie would absolutely destroy me in hyperspace. It sounds stupid but the little things come back to bite you. If I have my chin down and I'm in a slumped posture, I'll get negative thoughts. Chin up, back straight. If I'm trying to hide my usage from someone, I'll feel guilty the whole time. Don't hide your actions. The one time I ate a piece of chocolate and acted as if I poisoned myself. Eat healthily. Set and setting is an understatement.
If you have a responsibility and smoke deem instead, you might feel really bad about yourself. Get your stuff done before you blast off. If you wanted to get something done, but put it off, like say, working out, you might beat yourself up too much while in hyperspace, and that's not the place you want to be thinking negative thoughts. Make sure you're in comfortable clothing, there's been a bunch of times I had to strip naked to feel better.
Don't load up too much, know what you can handle and what you can't. A few mgs could be the difference between peace and panic. Don't do it for the story, do it to grow. My friends and I have had pissing contests and it always ends up bad for one of us. Clean up your living space unless you thrive in dirty conditions, under the influence, a messed up room could cause some bad emotions. If you feel the need to be alone while you blast off, be alone, if you're more comfortable around people, be around them.
Try not to burn your DMT, the worst times I've had where when I burnt the stuff, it could be placebo, but a clean smoke always felt cleaner. Be honest with yourself, ask yourself some questions, what do you want to get out of the experience? Meditate beforehand, calm yourself down as much as you possibly could. Open yourself up, sometimes if I cross my arms or legs, I'll become tense and restrained, but if I spread my legs and arms out and welcome whatever comes my way, I'll be less defensive and open to the experience.
Take that piss or shit before you think about blasting off, there have been times I couldn't stop thinking about taking a piss and I gained nothing from the ride, and times where these things even caused anxiety. Smell something amazing before going into the experience, look at your favorite picture of your dog, do whatever you can to induce a happy thought before you blast off.
Know when to stop. I've been deep into a session where I've taken hits for 2-3 hours chilling on my deck, and everything was fine until I took a hit I wasn't ready for. When you hear that voice say, "don't do it", listen. That voice knows more than you give it credit for. I've ignored that voice and paid the price.
Never fight the experience, this is possibly the worst thing you could do. Do whatever it takes to be open-minded, whether it's through posture, or thoughts. Work with the molecule, if you hear that voice saying, start pacing, get up and start pacing. If it says lay down right now, do just that. Don't be in a dangerous position before you enter hyperspace. If you're near something dangerous be with someone who can get you out of danger. There are a few posts describing how some have accidentally killed themselves due to being near fire or water. The whole point for this chemical is to grow.
Put on your favorite song, or a song that will induce positive vibes, or if you like silence, make sure nothing will disturb you. I've put on the wrong song a few times and was too deep to get up, and the whole time the song caused mass panic.
Create a place you know calms you down. Some tape pictures to their wall of things that bring them joy, some light candles, some sit in darkness, some sit inside, some outside. Do whatever it takes to remain calm.
Be forgiving to yourself. I've done some shitty things and when in hyperspace I often think about those things, but if you remember you're trying to be a better person, and you're not that person anymore, you could bring your mind to ease. If that doesn't work, say words with positive connotations. Stuff like love, joy, happiness, how you love yourself, your family, your friends, and even the stranger you don't know.
Get your hands on a scale and weigh your doses.
Learn proper breathing techniques, a lot of times, a lack of oxygen will cause anxiety or a general feeling of negativity. Inhale through the nostrils and welcome a full breath of oxygen.
DMT will make you realize things you never knew you could realize, it will put you in a hyper-aware state, it will force you to be aware of things you didn't know affected you. Discovering these things and fixing them is how I'm able to enjoy my time in hyperspace.
As a user pointed out, practice makes perfect, don't expect everything to be a smooth ride your first time. Learn from each experience.
Take breaks if the experience continues to lose meaning. It's possible to dampen the "magic" with repeated use. Abuse is never the answer.
Throw rules out the window and don't try to make everything perfect.
This is random, not very well thought out, and specific to me advice, but maybe you could manipulate it and tailor it to you. If I think of anything else, I will continue to edit the post and add advice, this is a never-ending, growing experience, and I want the best for you and me.
Like I said at the beginning, tell me what makes you the most comfortable, tell me how you get the most out of your experience, there's still a lot I don't know, and I want to know it.