Lesse..
First collection I can recall was a Penny collection, in one of the blue folder things. This was around 1971, so older ones were still around. Lost interest about the time I got the 1943 steel pennies. Don't recall every 'buying' any - just got whatever I came across, and the 1943 steel pennies were a Christmas gift.
Next was FAMOUS MONSTERS OF FILMLAND magazine, being a big-time monster kid. Childhood collection long gone, but have replaced all and gained a lot more. If yer a monster kid, you'll understand. If not, don't know that I could explain it. You kind of 'had to be there' for FM. Still keep this one going.
Stamps joined in when I was 13 in 1977. Rich kid friend converted me, we went to the stamp store together, mailed off a few first day covers, bought what little I could. High School, guitar/garage band, girls and trying to keep my grades up took over soon, but Stamps is one I kept coming back to through the years, through the ups and downs.. Lost almost all during a dark time, working on a 'good' collection now, looking for quality where I can. So this one is definitely live :) (Good thing, being on this board).
As stamps held their own, I found a used record store that led to my next two hobbies. I found that old (as in early 60's) albums and 45's were (a) available, and (b) not so ridiculously priced that I couldn't afford them. Life long fan since I was 9 years old of The Beach Boys, and found I could get tons of their original albums and singles cheaply. That collection is still going, but about complete - all I'm missing there are some of the 1970's singles on Warner/Reprise that sold about 10 copies each. Hard to find, and expensive when found (with LOTS of bidders!). Have all their albums, tons of bootl....um.. 'auxiliary' recordings, both studio and live, and an album autographed by all (and got to meet them on June 4, 1979 on official 'Beach Boys Day' in Los Angeles!).
The other thing this store (which was still there, last time I visited 'home' back in 2006) had was movie posters or current and recent films. Remember me being a 'Monster Kid'? Well, in 1979, you still couldn't get 99% of movies on VHS, that was still a few years away. I had some of the old Super 8 movies that were silent, black and white and 8 or 13 minutes, but that was it. But now, I could buy the actual posters! I went nuts at that place, between Beach Boys records and horror/sci-fi posters.
As mentioned, Beach Boys records and memorabilia, still owned, but not actively doing much as .. well, they aren't exactly 'active' anymore. Movie Posters? Kept active off and on, like stamps. More on them in a bit.
About the same time as FAMOUS MONSTERS, I gradually got into Marvel Comics. I bought a lot of those at the same time I was into stamps, but the comics kinda petered out when all the High School stuff started (and they also doubled in price about every 3 months around then!)
That was the basis before 'life' took over. Some popped up, some died away, some stayed buried for decades and came back later. Graduation, college, marriage at 20, divorce 9 months later (no kids, thankfully. She apparently thought the best man really WAS the best man...), joining the United States Navy for 4 years (around which time I turned my love of sports in to Baseball, and ordered lots of autographed photos of Hall of Famers and such), found a wonderful lady, got out of the military, she was killed by a drunk driver which pretty much took me 'out of it' for a decade or so.
Around 1998, job moved me to Dallas, and lots of disposable income got some hobbies started and other invigorated. Now I could get DVD's of my movies, so I went hog wild with that.
ebay made it possible to regain my FAMOUS MONSTERS collection, so that's when that happened.
Met another wonderful lady, and got married again in 2000. Good income allowed me to add to (a) dvd's, (b)movie posters, (c) stamps sporadically. Along came my son in 2002, and a lot of that expendable cash vanished (imagine that!).
To the current - we celebrated our 13th wedding anniversary this past May, our son is in the 5th grade and is a bigger baseball fan than me now. he's also getting into stamps with me ;)
Due to PNC bank defrauding us to the point of taking our house away, we are in the process of moving (about 80% done, but lots more to do!). Don't really mind, don't intend to retire in Fort Wayne. Nice enough, but don't like the cold winters (I'm still a Southern California guy at heart), so just as well not making house payments. Moving from a big house with basement to a not-as-big house with no basement. So one thing that was obvious is some of my collecting was now out of space. DVD's are easy enough, store them in paper sleeves and put the art and inserts in binder sheets for reference. Stamps, not a real space problem (at this point at least). The movie posters, however (a) were a DEFINITE space issue, and (b) were my one collection worth a LOT of money. Horror/Sci-fi posters are very hot right now. Soo, took a break from moving a couple weeks back to get all my posters collected (boxes, tubes, etc.) and packed them all up and shipped them off to be auctioned off during the Halloween Auctions by the biggest dealer in the US. Hoping for a very nice haul, but realistic it might not be as big as liked.
So, after all that...
I collect Stamps (US, and Worldwide 1840-1964)
I 'aquire' DVD's or Blu-Rays of genre films for my collection. Can't really say I 'collect' them, as I just get the ones I like.. However, with over 5000, I guess my standards are pretty broad

I collect anything new that comes around from Brian Wilson or The Beach Boys (though a new box set around $140 with only a few unreleased tracks is making me pause.. maybe if my posters sell for a ton).
I'm collecting more and more gray hairs all the time (gained a lot thanks to PNC over the last few years.. thanks a LOT, guys

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And that's about it - most of my other collections are ancient history (pennies) or replaced by modern methods (cheaper to read comics in trade paperbacks when the mood strikes). FAMOUS MONSTERS stopped publication back in 1983, sputtered back around 1990 in a much-publicized debacle, earing a deserved death around 2000, and is now back in a version much closer to the original, but without Forry Ackerman to run it, it's not the same, so my 'collecting' is down to the original 1958-1983 run.. and that is pretty much all done when my younger brother flies up here from California in June and we'll drive to Pittsburgh for a classic horror convention called the MONSTER BASH and I'll be sure to have my FM want list there

OK, I guess I've wasted enough pixels here. One things for sure, when I get to my 50th post, nobody will be able to say I got there with a bunch of 'yup' or 'wow, that's great' posts!