Great comments!
I think the fear we feel is our ego. It has a hard time letting go. This is what makes DMT so different from other substances. Normally, the ego wants more, it causes addiction. With DMT the reaction is the opposite. I'd say that DMT is not just non-addictive, its anti-addictive. Users find it hard getting themselves to use it, instead of the usual trying to limit their use.
Why do people keep on using DMT if its anti-addictive? It's the same reason people climb Mount Everest instead of going to Bali. It can be tough as hell, but the reward can stay for life. Thats the experience we seek.
I have the following advice:
1) Don't be hard on yourself and follow all advice given so far
2) Mentally preparing to the extent that you do is usually good, but in some cases it might be counter productive. The more you prepare, the more you inflate the scenario, the bigger the mental step is, the more resistance and fear arises. Sometimes its better to 'just do it'. Take a couple of minutes to mentally prepare before you light up and just go.
3) Preload with harmala (eg. 25 mg dose of Harmine taken sublingual 20 min prior to smoking DMT). This will get in a mellow state before you take off, eliminating some pre-flight anxiety. During the journey it will act as a warm blanket. With a pre-dose of Harmine I have no trouble accepting anything happening during the trip (including the fast onset), which I find difficult to do without.
4) Don't smoke freebase. Try changa (or enhanced leave) instead. I find the onset to be slower and easier on my mind. I don't like freebase anymore. It hits too hard. Most experienced smokers tend to stop using freebase after a while. For a reason.
5) (As already mentioned) start off with smaller dose first (eg. 15-20 mg).
6) Give it time. The more you do it, the more used you will get. A bit of fear will always stay, but it will become less.