your apprehension is totally valid. we all experience it, some of us on a regular basis. it's similar to climbing up on a ledge of a sky scraper with a parachute on. sure, we'll probably be fine but damn is that a long and possibly dangerous fall.
I always recommend you start slow and gentle. take less than you think you need. you can always add more next time but there's little recourse if you bite off more than you can chew. over time you'll begin to form a familiarity with the medicine. you'll start to understand how to handle it's nuanced behaviours and how to respond when you start to feel uncomfortable or overwhelmed.
the best things I was taught from fellow nexians and trip heads was to practice unconditional surrender. you can be firm and assert your beliefs and boundaries but understand, you are not in total control once you pass the gates of hyperspace. you are for all intensive purposes an unannounced guest in the beyond. many entities will be welcoming, some may be confused, others might be a bit... i don't want to say offputting but less accepting. you might see things that are a bit jarring or overwhelming. in these instances I find that it's best to sit back try and relax and remember "it's going to stop soon".
some things I always try to mention that would be good to take into consideration:
~trip sitter - do you have someone to essentially act as your care taker / baby sitter incase something goes wrong? when you're in hyperspace your understanding of fine motor skills and decision making capabilities are a bit skewed, something as simple as kicking a candle over or a glass can have serious consequences and having a trip sitter not only helps eliminate unecessary risks of harm but helps make sure the trip goes smoothly. there's nothing in my opinion more uncomfortable than an unexpected guest or suddenly getting thirsty mid trip and being incapable of handling that.
~set and setting - is the planned environment clean, free of dangerous items like weapons, sharp objects, things that can be shattered, ignition sources like candles, unpredictable animals and so on? we want our environment to be clean and healthy. personally, my "group" likes to deep clean the entire house, get it smelling good, throw down some fluffy blankets, put some (pre - screened) music on, and some ambient warm color light. this makes the whole ordeal much more comfortable and welcoming
~mindset - are we in a good place mentally? it's usually not suggested to go into hyperspace in a less than stable mindset. I, personally, do trip in less than optimum mental spaces. but that's only because I have years upon years of experience tripping primarily alone for therapeutic and legitimate medicinal reasons. my word of warning especially if you do go into this space in less than stellar mental space is that you adhere by ALL other suggestions i've listed. one poor decision is all it takes for great and irreversible harm to be done to oneself, property, or others. a good moment should be taken before a trip to consider "what am I looking for, what am I doing, what do I hope to get out of this experience?"
~journal - as listed above, take a moment to ask yourself "what am I doing this for?" and think about it for a bit. sometimes I spend an entire day or more before a trip pondering this question. i've taken over a week to think about this before in the past. once you have an idea it's good practice to write down your question, intentions, and goals in a private notebook free of any other writing. put the time, date, what's on your mind, your intentions and goals etc. write your intended dosage, administration method, who's with you during the trip. when you come out of the trip take a few moments to think about what you saw in as fine of detail as possible. these experiences are incredibly fleeting for most people especially when they take more than they probably should (which is why I HIGHLY recommend starting looooooooow, you'll remember more and its a skill that will follow you deeper into the higher dose space)
this journal will help you navigate your time in the hyperspace realm and give you more context over time as to where you are and where you came from in this whole thing. it can also be used as a tool to help you find your way, the way you prefer to get the experiences you're looking for rather than a constant shot in the dark. i.e. for myself I know I like to take my dose outside the back door and then slowly walk in and lay down on the couch on a really fluffy blanket in the dark with orange and red light and gently house music.
remember you are soley responsible for your safety and wellfare. none of us can protect you from yourself. if treated with respect and caution NN-DMT can be an amazing medicine. if disrespected and treated negligently it can teach you serious and harsh lessons that will almost assuredly scare you away from it.
hope we see you around in the coming months, don't forget to read this
Attitude Page - DMT-Nexus Wiki and read/ socialize around the nexus a bit before you jump in. this isn't for everyone including those that think it is so take some time to get to know us and the medicine.
best of luck,

NeitherHere