Bike check
There's no point in reinventing the wheel with this one so here's a quick rundown of a basic bike check from Tredz. Check your bike before every ride and do a more thorough inspection before those epic rides.
I would add two things here though. 1) Check your brake pads, they may be fine now but will they last the entire ride? Rim brake pads have a groove through the pad, when this has worn down smooth it's time to replace the pads. Disc brake pads should have at least 0.5mm of pad on either side (don't include the backing plate in this measurement). Removing the wheels will make this check easier.
2) Pick your bike up an inch or so, let it fall to the ground and listen for any unusual noises. You'd be amazed how many faults can be found with this!