Just wanted to get an idea on what stage of collecting you're at?
I remember how my collection started; I was 9-years-old and and I found a dollar bill, one that I haven't seen in ages so I exchanged 1 dollar for it and treasured the note. Then I found a similar (1974) $2 bill and it went on. When I saw a 1954 note for the first time, I think it was a 10, that note was like the rarest piece of scarcity I had ever seen.
For years I would go hunt in downtown with my parents trying to find "old bills". Usually nothing older than 1937. Some stores had good deals where I would almost always buy stuff at near face value ($20 notes for $27 and such), some stores did not give bargains and charged taxes on top.
Now I have several UNC and AU of each of the multi-colors, I have several of each note in the 1954 series (at least 1 UNC of each), I have all the 1937's in high grade, plenty of 1923's, each one of the 25 cent notes and a few in the 1935's.
I know some collectors have a whole bunch of the "series" (1937, 1954, 1970's, birds) and are looking to collect/trade the rare high denoms of the 1935's. Some collectors are even more advanced than that and go into the extremely rare notes like the $25, the $4, the 19th century,.... Some are just very picky about the grade they buy in.
So I was wondering what you collect, how often you buy/sell/trade, what type of denoms you collect, do you do it for investment purposes, for plain sitting-in-the-closet, do you impress your friends? Or what?