There are a lot of different hand pumps out there, so choose wisely.
When I go for a road ride and I’m out for a while I generally take a frame pump that mounts under my top tube. I also carry two tubes and a patch kit to be safe. The beauty of the larger frame pump is that it’s always up to the job no matter if you flat once, or have one of those triple flat days. And you never run out of air, unlike CO2s.
The frame pump I used is made by Park Tool. I like it over the other popular Topeak pumps because it’s adjustable in length and has better ergonomics.
If I’m going on a short ride and I feel like being lazy, I’ll go the CO2 route. But I always will carry two cartridges, a tube and a patch kit. One can never be too prepared. I also carry boot material to help patch my tire if it rips, which has happened. If you don’t have boot patch material, you can use the trusty dollar bill method or the wrapper from your snack of choice.