Right well:
- service the car often. What makes a flat battery is: taking it for lots of short journeys; cold weather; damp; an aging battery; bad alternator.
- turn the lights, radio and any electrical items like heaters off when engine not running.
If you do all the chance of needing a restarter is very low.
Chances are, if you are attentive to maintenance and to vehicle handling, you’d end up helping others more than your own needs. As a cyclist I tend to help others for their lack of tools than I use my carried tools myself on my own bike. I service my own bike.
It is good to help others. They might not have your level of attentiveness to details (for lack of care or just a very busy life).