One favor you can do yourself is to start patching your tubes if you're not already doing so.
Over the past 20 years of riding a collection of ~10 bikes, I would be lucky if patching tubes would have saved me even 200 dollars. What your time is worth to you may be different, but for most working adults I don't think patching makes time-money-sense. Assuming you already have a pump, instead of ordering a patch kit to carry with you on rides or keep at home, just order one of whatever tube your bike needs (usually ~5-9 bucks), some tire levers (reusable, 5 bucks) and keep in drawer until day dawns you need it. The rare time I buy a new bike with a weird innertube I don't already have, I buy a couple of spares immediately with the bike.
Each person has to satisfy their own sense of time and money, which I suspect is partially subjective for most of us. For instance I actually have spare time, and am not paid for working extra hours on my day job. Admittedly, being self sufficient for bike maintenance is part of "life" for me, and even when my kids needed more attentive care, I was always able to carve out 15 minutes to patch a tube.
Paranoid me always carry two spare tubes, a patch kit and a puncture repair spray (it's supposed to inject a product that reinflates the tyre immediately, allowing me to keep riding and then go home without having to repair or remplace the tube, but since I've never had the opportunity to use it I can't tell if it's really effective).
Where I am, in the south of France, as well. And they are of the really aggressive species!
I do run latex on my gravel/cx bike and those go into the trash immediately as they're far more difficult to properly patch. Hurts a little more when you pay 2-3x the price though :(
Everything else, check. Roughing up the patch area, waiting a few minutes for the vulcanizing fluid to dry, squeezing the patch for a few seconds after applying.
I've never had a problem with the little sandpaper that comes with the kit.