I do light credit card touring.
Seatbag
Handle bar bag.
Carry a set of casual clothes and shoes, spare tyre and tubes, tools and toiletries and a few gadgets.

I've just got a large Ortlieb saddlebag and MTB shoes/pedals.

I generally run puncture resistant 25c tyres and drop the pressure 10psi.

Bike handles fine with this stuff on. Bit slow up the hills and that seatbag is a bit of a sail (hence the switch to the ortlieb).