Welcome!
I've been collecting since 1972.
US, pretty much anything in Scott's US Specialized, with a few exceptions (e.g. embossed paper, encapsulated, UN and a couple other). Although, I do have some topic related foreign issues (Joint issues, Masonic, space and other).
I generate my own home-brewed albums, and also use stock books and card boxes.
How many...? a few.
Which doesn't count the postal related collectables such as press blocks from catalog printing, mailing tubes from the 1800's, figurines, etc. I'm not home right now but this is just like my favorite figurine which was given to me by an Uncle about that time I started collecting.

My uncle was a postmaster, now retired. My sister just retired from the post office and my son-in-law just started... But I don't really count them as part of my collection... they object when I try.

Jeff