Pretty much all there is to be said, it depends on what scene you are in; if you are very peripheral or not involved in any psychedelic drug-taking scene there is a high degree of probability that you are going to get ripped off. If you buy your drugs from the Internet, there is a high degree of likelihood that you will not get what you were asking for, potentially fatally and a 100% chance that you are now on some sort of list, you're just too small fry for them to bother with you. Plus, remind yourself that you are literally buying drugs from an email address that you have no relationship with whatsoever. Scratch the fuck out of that, for classic illegal drugs (including LSD; that is, anything that your parents may have heard of, and is not, say, a ridiculously-substituted cathinone or whatever that probably sucks anyway) anyway.
So really, the only thing that you can do is introduce yourself to the appropriate "scene," unfortunately if you don't like the music, think hippies smell, whatever, you're going to decide if you want to put up with all that just to find some drugs; otherwise, if you are into that sort of thing, then "dry" just comes and goes and yes, in fact, it is a seasonal thing with the deadass end of winter probably being the lowest season of availability. Otherwise, though, it is ridiculously easy to score these sorts of drugs at the sort of venues that you would expect, however, now with all the bizarro-land shit that's out there, you have to be very, very careful, which preferably means testing both for a positive Ehrlich and against certain colors on the Marquis reagent (if you don't know what I'm talking about, look it up before you go any further); you will be better off buying from older people who are not junkies and just seem legit, although if you have no experience with the scene obviously that doesn't do you very much good, but, if you are, you'll be better off buying at least a sheet, getting a small amount beforehand for an either subjective or (preferably) objective test.
But if you're not from "the scene," tread very lightly because you are on other people's territory and many people will look look down on you as a custie and someone who can be ripped off for money, unless you can successfully impersonate someone who knows what their talking about. Most of this would really apply to scoring any drug, but LSD in particular. It is part of a rather insular scene, or rather, a few rather insulated and somewhat overcrossing scenes; if you go to large, open air, drug oriented festivals or something, obviously getting offered the stuff won't be an issue but making sure the stuff you're getting is legitimate is (see above.) If you're talking about something local or smaller scale, again, it's about scene and being a member of one of several quasi-overlapping subcultures. If not that, then it's going to be down to trying to approach people who seem likely candidates (impossible in some places in the country/world, less so in others) or having the good(?) fortune that some other way you find a connection (if your friend is going to one of the aforementioned festivals, or if your pot [or whatever] dealer has it occasionally, or you bump into and meet someone, or whatever.)
I made a long, somewhat satirical post about this subject a while ago that I think would be worth adding here. I'll look for it.