Visualizing approaching death positively is super important as far as I'm concerned. I recall an old "happiness generating" practice I used to do and that comes in handy in this regard. It was cold generating happiness without relying on outside factors, the way we usually conceive happiness. Happiness is an energy that can be tapped by not being afflicted or attached and just letting it emerge, accepting it despite counter outside factors, including death.
I visualize or mentally rehearse the death process with the Tibetan Book of the Dead and Sogyal Rinpoche's Tibetan Book of Living and Dying as guides or templates. I don't take them literally, but I use the descriptions to help envision what I think it might be like for me to die. I agree with the notion that the death experience is not the same for everybody, rather it is informed by the subjective person, including psychological make-up, beliefs, overall life experience, circumstances of death, what was eaten for lunch, etc. Someone dying peacefully in a hospital bed will have a different death experience from someone being murdered in a violent crime or in a war. Two people sitting next to each other in a crashing jetliner, one of whom is a long-time mindfulness practitioner, will have similarities in the death experience because of the manner, but how they go through it would be different. Just for the record, I don't think I know what I'm talking about.
Although I think subjectivity may inform various aspects all through the bardo experience from death to re-birth, I also think that maybe the overall structure of the bardos as described in the Tibetan Book of the Death is universal, and whenever something is described as happening, something is happening but how that something appears depends on the previous and future lives. As much as I dislike the idea of imposing my beliefs on the rest of humanity, if I believe in reincarnation because it just makes sense as a natural cycle, one of the many that we see in nature, then I'm positing that it happens to everyone. We're all part of nature, regardless of belief that we are not, that we are somehow special and above it. Even a bardo experience of going to heaven and meeting God can occur as a result of strong belief and expectation during life, but then it will melt away like a reincar-ception into the bardo of re-birth and the process of reincarnation, with the last remnant wisps of the previous life wiped away by or at the conception of the next life, only taking karmic imprints into the new life. I did mention that I don't really think I know what I'm talking about, right?
The many near-death and death-revival accounts that exist may suggest the subjectivity and diversity in experience in just approaching death. Those accounts, often described as varying degrees of peaceful, may just be skimming the surface, either going deep into death with critical functions stopped but not for long, or being clinically dead for a longer period but not so deep that they couldn't be revived. By nature they did not go so far where the brain structures that support life processes were destroyed. Still, I think our mode of existence and being is so habituated (ego) that there's a lot of momentum of subjectivity that goes deep into the bardo experience.
Beyond near-death and revival experiences, when brain and physical sensory processes definitively stop functioning, I think we go into what the Tibetan Book of the Dead describes as the outer and inner dissolutions which may be less affected by subjective experience. I think even the habit consciousness of the vast majority of people fades to black, maybe because it can't handle what's happening to it. I might even say the dissolutions characterize the end of awareness. The only way to maintain awareness is through training and practice while alive to prepare and recognize it when it occurs. And even then the death experience as described may be so overwhelming and disorienting that recognition isn't necessarily possible (spontaneous recognition, however, is still possible because anything's possible).
The Tibetan Book of the Dead makes sense to me when it describes parts of the bardo experience as being extremely disorienting and confusing. I imagine it would be. Our habituated existence has always relied on sensory input processed through our brains to form all of subjective reality. Very stable. At death, the senses stop reception, the brain dies, reality fades away, and all that's left as described in the book is a non-corporeal habit of subjectivity feeling like it's blown about in hurricane force winds.
All of this is just my own little thought experiment; envisioning a scenario maybe a way of trying to be prepared. Everyone who does this might come up with something completely different. Very little is narrowly defined, I think, in the bardo. The subjectivity of the death experience might also include the sequence of events. They don't occur in one uniform way and may not be clear-cut. I heard one lama talking about the dissolutions starting even before death, and listening to that I couldn't say I disagreed or thought it was wrong. I thought it was interesting, a very broad interpretation. And the bright light many people attest to and the calm that comes with it may also be related to the dissolutions, which I've contemplated as beyond the point of revival.
All of this is contemplating just the death point bardo, the first of three death bardos. I couldn't do this sort of thought experiment with the remaining two bardos because I don't have any real insight into them to add to what the Tibetan Book of the Dead already presents. Doing a personalized version would be like doing a bardo version of the Divine Comedy, and as much of a big joke my life has been, I'm no Dante. The death point is something we're all eminently qualified to contemplate, because it's something we will imminently expect. No one has to believe in anything in particular to contemplate it.