I find I'm highly interested in pharmacology, and were I not studying my current field I would probably be in that. I know that in months not immediately before and during exams, I may well spend more time studying pharmacology than law.
I spend ages researching drugs that sound potentially interesting, and at parties or when doing drugs with friends (particularly when someone hasn't tried the drug in question before), all eyes immediately turn to me, awaiting a lengthy explanation about what it is technically, how it works, what it will actually feel like, how long it will take, and any possible contraindications, as well as possible potentiation methods or suggestions for synergistic combinations. While I think all find it useful and almost everyone takes it very light-heartedly, it's sometimes a little funny to get laughed at for researching specific stuff, "needing to know everything possible about drugs", knowing about all kinds of receptors and agonists and enzyme inhibitors etc. They usually shut up, though, when I offer my usual retort on how despite how extremely unpleasant and torturous I find the task, it is a lesser evil than dying because of some stupid shit like taking a drug that doesn't go well with the medicine you're taking.
If I feel really unsure about the drug or fail to find adequate information, I will read second-hand reports, Erowid experiences etc.; otherwise I try not to give them too much value, as I don't want my expectations to affect my assessment of the experience. I might do a bit more of this for combinations of drugs, as there is less formal documented evidence, and much less for psychedelics, as I find that my response to them is particularly sensitive to prior expectations.
All in all I highly recommend that anyone who does drugs does at least basic research on drugs they are about to ingest, at least for the sake of fundamental harm reduction, even if they take no further interest in pharmacological details. I would go as far as to say it is stupid to take drugs without doing any research, and a metric shit ton of people are lucky to be alive.