check and adjust your tire pressures prior to the trip, including the spare. ensure that the vehicle is in good working condition (of note on the highway: all headlights, parking lights, signal lights, and taillights are working well)

bring along a tire-pressure gauge and a set of jumper cables, aside from the basic tools and jack.

observe proper road courtesy: observe proper lanes, signal when changing lanes or overtaking, use high beams and fog lights properly, etc...

in case you feel sleepy while driving, immediately stop at a safe place, then maybe rest, or grab a coffee, or something. it would be helpful if you have a companion on the road who can converse with you continuously.