basicly if you can provide items that fill basic needs requirements: food, shelter, clothing, entertainment (music, drugs or alcohol, "companionship", ect) or items that enhance or enrich these basic needs you have a more secure future. don't think in terms of being employed, think of being self-employed.
i suggest having multiple job skills. perhaps planning on a job for the decline (such as the wind engineer), and something post collapse such as a broom maker/soap maker/ect. a lot of the decline jobs require some sort of manufacturing base and modern equipment. they also require a desire and need to continue our present lifestyles uninterrupted. that trend will continue for a while but it'll be phased out as our only-made-to-past the warantee-and-then-break manufacturing philosophy comes back to haunt us. i feel we should use what we can from our present society, but have the wisdom to abandon it when it is no longer an advantage.
post-collapse, any tax collectors, regulators, politicians, or other societal leeches should be disregarded as compost. i, personally, have had more than enough of our government, its hangers on, and its constant regulation of me. i am the adult of our species, dang it! if i am not hurting anyone or anything else then leave me alone.
if you have a usefull skill or the ability to learn a skill, i want to be your neighbor. if you have no skills and no desire/ability to learn any, you are a threat to my survival as you are depleting tenuous resources. i admit i'm a tad militant, but i also feel that a candid look at the people around you will make you realize how useless and stupid most people are. cold and harsh, i know, but justified. FAR too many people are only good at managing managers, shuffling paper, and kissing butt. they won't be able to make the mental leap back a century or 5. and not everyone can survive anyway, so it makes logical sense to help anyone who can help you.
personally, i'm a horticulturalist by vocation, but a farmer, blacksmith, and general handyman/laborer by advocation.
but i do believe that after the turmoil settles down, a risky but profitable job is a trader. being near a navagatable river allows you the opportunity to trade with distant people. certain items will only be able to be gotten this way. it'll be risky, but profitable.