Ok, so I go online to find a good summary of impartial information on what DMT is about (the lack of negative health effects associated with it, etc.). And in my interweb wanderings, I find THIS:

As for extraction methods there are quite a few ways. People have been known to extract DMT from human brains (rare), animal brains (uncommon), and surprisingly blades of grass from your lawn (common). The blade of grass extraction method brings me to my next thoughts however I'll start by explaining how it's extracted. First you go out and grab a bunch of blades of grass. Second, you must freeze them and then crush them until they are liquefied. After that you keep crushing the grass and keep freezing them over and over and over and over again all while simply changing the ph levels and keeping them at a ph level of 9. After a looooong process of treating and fermenting the grass, you are left with crystals that you are able to smoke.
(source: Cracked.com Article)

And if things begin to feel dark or overwhelming just keep reminding yourself;

The experience is going to escalate at a rapid pace - go with it. Trying to stand your ground at the peak of Niagara Falls is going to prove more difficult than riding the water's current. You're here to watch and learn, not to exert your will.

“Don’t be so quick to call this a bad trip. Just stay with it for a bit, take a look at it." Take a deep breath. Are you experiencing tension or anxiety? Why is that? Ask out loud, "Why am I experiencing fear?" or "Show me love instead." Or say nothing at all. Size things up -
“Follow it back to the root." What is causing that negative entity to drip fungal plasma into your soul? Ask the entity. There's a reason you're seeing what you're seeing right now, and if you can get to the root of it, you're well on your way to total integration.

There are plenty of navigation mechanisms. These are just some of mine. The most important navigation mechanism if you do start to feel uneasy is to understand what direction you need to drive forward in. A lot of times people are seeking out. (“I want out of the experience, I want to be out of my body, get me out of this…”) This is a profound transgression against the directions of the grain. You do not go out, you go through. Through is present. In the Inferno you can't escape Hell from the sides, you need to go right through the whole of it. Hyperspace can be like Dante's vision in this context.

And finally, the most tried and true technique if the darkness really has begun swallowing you whole? This is of critical importance to be remembered if you find yourself in the worst of all potential scenarios; The Dreaded Hyperslap. Any anxiety after you blast off or at any time during the journey can be lowered by humming deep and long, getting vibrations from the throat, and it feels quite amazing seeing its efficacy in action. Terence McKenna advocated for singing, but when I'm petrified the last thing I want to do is try and figure out what song I know the words to, and this deep, resonant hum will do the job just as well.