This is a challenge in development, so all suggestions are very welcome.

Start by creating a single sim (male or female). All characteristics are up to you - I prefer to use random tables for most things just to keep it interesting. Move them into their first home and have them select a job immediately - any of the jobs listed in their first newspaper. Then make a sim of the opposite gender (or the same if you want to end up with a same sex couple) and do the same thing. These 2 sims are destined to fall in love and marry, live together, perhaps have children. Starting the 2 off as separate individuals allows them to progress in their careers and accumulate funds. They should NOT be in the same career.

Play as you would normally - meeting needs and wants, making friends, etc. Your couple can move in together, marry, whenever you'd like.

The challenge part of this is that both of these sims really need variety and challenges in their careers. So everytime they achieve a level high enough to unlock the career reward, they switch jobs and start at the bottom again. Having kids may slow down their careers, but that's just like real life, right?

Be sure that their home has lots of space to hold all the career rewards you collect over their lifetimes! Scoring consists of simply seeing which rewards (and how many) you can earn before your sim dies of old age.

Cheats allowed would include those related to decorating, social interactions, money, etc. Using the cheat that allows promotions without having to make friends would make this much easier, so it's up to you to use it or not.

This sounds fun! Would it be "cheating" to skip a step, and just start with a couple from CAS?

I suggested starting with two separate sims just because I enjoy the courtship phase and because they will end up with more money than they will as a couple.

Could you start the couple on a college lot and then have them marry/move in together once they graduate?
Great challenge, by the way. When I stop getting addicted to my 100000 other ones I'll give this a go for sure

ooo this is a good idea!