What do you pack in an ideal hiking/outdoors/everyday first aid kit?

I live in a rural area and bike around a lot so I usually have a backpack on to carry things that don't fit/I don't feel assed to put on my cargo rack or I need to take with me when I'm walking and such, and I was thinking of adding a first aid kit to my backpack, wondering what good things I should have to be prepared, something that works as a general purpose since I usually wear the same pack when I do things like camping and hiking as well.