Adding a vacuum check system (another happy Leak Sentinel user!) was the best thing I have ever done for peace of mind. Remember to activate every control button or lever once the light is blinking green, just in case a fault only appears once something is moved.
Always taking a test photo (not just testing the strobes) has prevented me from forgetting about the lens cap and from leaving important bits of the system on shore more than once.
Never cleaning o-rings or grooves with cloth or Q-tips means not having to worry about stray fibers. Foam makeup brushes and wedges are absorbent, cheap, and really effective. I use something like these, readily available at pharmacies: