Answering as if the scenario is you have made it out of the city and are not in immediate danger. bushcraft engine repair/ auto mech construction
Only skill set you need is the brain power to know that zombies aren't real... You want to do a skill set challenge, at least make it a plausible one.
If you survived the first wave, it probably means you're proficient with weapons and self defense, so: Wilderness First Aid Orienteering Home Brewing Honorable Mention: Not coming off as a creeper when you encounter scared and single females.