I have just used a spreadsheet with tabs for different items. At this point, I just have one tab for vintage that lists everything I have in that area since it is mostly just the 3 3/4" figures and the 12" figures. For other stuff I have tabs for 3 3/4" OT and prequel, 12" for both and misc. (ships, beast packs, etc.) for both. Also have tabs for Legos, Hallmark ornaments, replicas, books and comics, loose figures, etc. For figures I would track name, cardback type, serial number, and price I paid. For other items, I have different columns, like set number and block count for legos or author for novels and comics. Last tab is a running total of all of my items, mostly for insurance purposes.