My general leaving the house three-point-check is
If I don't have pockets and will need my hands free, I put everything in a small black messenger bag.
If I'm going somewhere that means I will have time to kill, there is always a book packed.
On Fridays, when I teach out of the house all day, it's all of the above, plus food for cooking lunch for the 30 or so folks in the school house ( I teach cooking/serve lunch) plus water bottles and layers for my daughter and I.
Other than that, I work from home, so I am relieved of the duty of packing myself up for a day.