ORIGINAL: Luchnia
The best path is to pay close attention to any changes in your planes characteristics. Are there different sounds, change in vibration to the airframe, servo acting strange, was that a flutter you heard, landing gear secure, engine firewall solid, engine smooth as normal, servos solid in their mounts, all screws tight, etc.? A watchful eye and ear will keep you flying longer with much less failure and will minimize risks.
In the interest of full disclosure, I recently had an experience where the "watchful eye" saved my big investment (30% PRC Yak 54). I noticed as part of my preflight checks that the spinner appeared to be vibrating excessively. Further inspection revealed a cracked firewall support. Had I flown the plane, chances are the firewall would have come apart completely and I'd have lost the plane.
The only redundant system I installed was the switch. I have a single battery that goes to two switches, and both provide power to the same reciever. I subscribed to the notion that the switch is the weak link in the chain. With two switches, its easier to identify a failing switch, and by checking each switch on startup, I improve my odds of finding it before disaster. Batteries are A123 that I keep track of the capacity. Voltage feeds back to the transmitter real time, and I know my "no-fly" voltage.
The trick is knowing what behavior your plane exhibits, and when its different, finding out why. Does the radio glitch if the switch is jiggled? This is usually the first indicator of a worn or failing switch. Do servos glitch when wires are shaken or tapped? Is the plane vibrating more than it used to? Does it sound the same?
Brad