Tired of unexpected repair bills, trying to get smarter about car maintenance

It feels like every few months I'm hit with an unexpected and expensive repair bill for my car. Just last week it was something with the suspension, before that it was a coolant leak. I'm clearly not doing a good job of staying ahead of problems and I want to change that. I've been looking into general auto repair prevention strategies because I'd much rather spend a bit on regular checks than keep paying for big fixes. The challenge is I don't know where to start. Do most people here follow a strict schedule based on mileage or time? And how do you know what to actually look for or ask a mechanic to check during a service? I want to be more proactive but I need a practical plan. What actually works for people to catch issues early before they become emergencies?