I only had one last year (puncture that is) and two the year before, so I've almost forgotten what I do. They all happen on the canal towpath which is the worst place known for repairing anything. I also let a woman who'd gone out with no means of repairing a flat tyre have a brand new tube (which I even put in for her!) in exchange for her holy one. She bought me a cup of tea afterwards which cost her more than the tube had cost me.
I carry 2 spares and if I have one 1 is a repaired tube, also a repair kit, and like others above do repairs at home. If I had 3 punctures I'd have to fix it on the road.
Unless the puncture is in the outside half of the tube, away from seams, away from the valve and straightforward I discard the tube, so usually that means it's replace and discard. Plenty of second uses for them if they are discarded.
I have a spare wheel and old tyre of each size, and check the repair on those. If a repaired tube doesn't stay hard for a week it doesn't get re-used. I don't care how many patches there are, if it passes that test it's OK.
Don't do expensive patches. the SJS ones I bought for 99p seem to work fine. The
Halfords ones in the pack for the other bike will probably be fine too - haven't opened the plastic case yet though.