The general consensus (with good reason) will be two things:
1) Read the FAQ located up the top, reason it's referenced so much is because there is a wealth of information. And I've asked some doozies lately. Best advice when it comes to asking questions that I can give is try what's written on the FAQ, do a google search if you can because it will link back to DMT Nexus for the most part, and show where you might have a problem, outline what exactly you're having problems with (for example if I say "no crystals" I would get pointed to the FAQ, if I say "I have done steps 1, 2 and 3 from X guide, steps 1 and 2 worked as described, but step 3 resulted in [insert image or description here], where did I go wrong?"
this will yield a better response and probably save you a hell of a lot of time and frustration.
How do I know this? Well because I have asked some doozies like I mentioned before, and I asked some where if I had have re-read through the FAQ I would either have the answer, or a solution, or at the very least know that asking something really generic isn't going to help anyone. This is more of a general advice answer.
2) To answer your question about decreasing the temperature, there was a post here (after I did a search), where no noticeable or meaningful result occurred from lowering the temperature of your apparatus. Not only that but time is needed for a proper structure to form from the DMT, that takes time rather than temperature. I would suggest looking at different TEKs, I haven't really been looking at many outside of the one that is of particular interest to me right now, maybe there's one that requires less freeze-precip times. I can also say that if you're using an NPS and freeze-precip, depending on the container you're using to freeze-precip will have a big impact on the result you get, it's very easy to run through a TEK and have too much NPS at the freeze precipitate stage, so be mindful of that because no matter how cold (based on conventional refrigeration) you can get it, you will encounter a result you do not desire.
The other thing I will say is that speed will probably come with experience, the more you know and whatnot. I would actually be very interested to hear people's first time trying to make their own and see their stories.