I dislike the term "DIY." It reads just like "bodging it," to me, probably because that is exactly what it is.
There are very many accident reports where a highly experienced crew, one that knew the area like the back of the hand, made a wrong assumption about where they were.
There's no substitute for flying a legal approach, one that has been surveyed, charted and approved, using the equipment legally required for that. That is not to say that we can always do that, of course, just that it's inarguably the safest way to make an approach. Once you depart from all those niggling legalities, well, you are now swimming rather than being on dry land. Then it's just a matter of not going in over your head, I guess.