My kit is WAY overboard, because my stepfather was an EMT and he built it for me based on all of the most common /out/ injuries he's responded to over the years, but for at home kits you really should be able to get by with just a really good assortment of various Band-Aids, definitely not neglecting butterfly closures as they can really help keep small but deep wounds closed until you can get them sutured properly. On top of that, several sterile gauze pads, gauze rolls, medical tape, exam gloves, alcohol prep pads, aspirin and non-aspirin OTC painkillers, and a basic first aid booklet. Maybe some topical antibiotic ointments.
Basically look around your house, think of all the shit you do on a daily basis, then imagine the absolute worst that you could realistically injure yourself, and all of the most common yet minor ways you could injure yourself. Now plan for them, buying the bulk of the supplies intended for the smaller common stuff, but still having enough to treat the big cataclysmic (yet realistic) shit that could happen but make sure that the small stuff won't deplete your supplies for the big stuff.