When modern society collapses, the infrastructure that supports most of our modern commerce will go with it. This means that a number of the jobs that pay the most right now (banking and IT) will become worthless and the jobs currently paying some of the smallest salaries (building and mechanics) will become the most valued.
This means that the prudent preparer, if they fall into the first group, will make a contingency plan to ensure they posses a craft that is valued in a post-collapse world. While you don’t necessarily need to trade your pinstripe suit for a pair of overalls right now, there are a number of trades you can learn now in order to arm yourself with practical skills that will be valued in a world without technology or modern infrastructure.
Auto mechanic – even people in a post-apocalyptic world will like a little muscle under the hood, especially if they need to travel long distances over land. There is also the possibility that computers in cars will stop working (such as in an EMP blast), so good ol’ fashioned mechanics skills will be highly valued.
Blacksmithing – without modern computerized factories to produce things, people will rely on metal blacksmithing to produce tools and repair the items they already have. Given that there are few practicing blacksmiths currently in existence, this skill will be in especially high demand.
Carpentry/Masonry – after the immediate panic of a societal collapse subsides, people will want to start building again. Carpentry and masonry skills will be highly valued for repairing or building homes, barns, and other structures.
Gardening/Farming – absent a local grocery store, people will have to start growing and harvesting their food again. Someone with agricultural knowledge, let alone tools and machinery to produce extra food for sale, will thrive in a post-collapse society.
Medicine – people always get ill, especially so when the infrastructure keeping them healthy now break down. One of the highest valued skills today, doctors, nurses, and even those with elementary medical training will be highly valued trade partners for those with a disease or sick family member.
While there are others that could be added to this list (HAM radio expert and school teacher among them), this is a good start. If you have a trade I missed, or you would like to add, please contribute in the comments section below.