The surest way to avoid leaks is to use primary lithium batteries. Energizer Ultimate is the most common brand. They are far more expensive, but last 20+ years, have significantly higher capacity, and will protect your gear.

The other sure way is to take batteries out, at least out of items you are unlikely to need on a short notice. So, my bedside flashlight is gonna have batteries in it, but the one I have in my car evac kit, probably not.

Beyond that, the most important piece of advice I have is to stick to brand-name batteries, rather than the cheapest option. While I had Duracells leak, it happens a lot less commonly than with fly-by-night brands. And rotate them every year, whether they need it or not. The cost of throwing out several good batteries is much lower than the cost of replacing the electronics they're in.

It can be beneficial to apply some rust preventive to the electrical contacts that are most likely to be affected by leaks, but I wouldn't bet my life on it. Also, keep in mind that aluminum enclosures are very vulnerable to the alkaline solution coming out of batteries. Plastic and steel are likely to survive mostly unscathed, but I had an aluminum Fenix battery basically chewed through.