My sim's teen daughter is already taking full advantage of her father's mixology.
My self-sim in Sims 3 and his wife are both authors, although he is rather a bit ahead of her in their career. Self-employed professions came with the second expansion pack, Ambitions, although you could earn money from writing even before and still can without it. You just get a stipend when you advance in your career, and titles and stuff. So it is not a super big deal if you don't have Ambitions, although it is probably my favorite expansion still.
The trump card, however, came with the Late Night expansion. Mostly famous for its vampires, celebrities and bars, it actually includes a skill that borders on cheating when you reach a high level: Mixology. Bartenders have it as their primary skill, but you can also buy a bar for your home and mix drinks there. At first only ordinary drinks, then party drinks which do little more than help your parties be successful. But then come the drinks with effects.
Skill Booster gives a modest increase to gaining skills, kind of like caffeinated drinks in real life. Next up is Romantic drinks, which ... well, they seem to reduce certain inhibitions. They aren't exactly love potions, but they make romantic progress go faster. After that is Energy drinks. These have little effect if you are well rested, but when the energy starts to get low, energy drinks will make the final inch last for a mile. You can continue to work for several hours after you would normally been asleep, and you won't feel tired until you are all out of energy. (More caffeine, I guess.) Next is the Sorrow Annihilator, which I rarely find a use for. It seems to be very narrow, only removing breakup pain.
The final drink is the Crazy Mood drink, and it causes the fun bar to gradually fill up over time until the drink expires. At that time you get a small negative mood for some hours, but it is pretty mild compared to the big bonus. Writing is normally an activity that drains fun in The Sims 3 (possibly also in real life, if you write for a living), so you have to take breaks and play or do something else funny for a while. With the Crazy Mood drink and the Energy drink, you can stay up all night writing happily. That translates into money and fame pretty quickly.
The final secret weapons came with the Generations expansion. It is a chemistry set which lets you discover various potions. I already mentioned that the highest level potion can rejuvenate a sim, and the second highest can make imaginary friends real. But the one I use the most is the sleep potion. It lets you compress eight hours of sleep into two, or something on that scale. My sim also has the "meditative trance sleep" bonus, which cuts sleep time with 20%, but that is pretty small compared to the better sleeping through chemistry.
Between all of these, Sim-Magnus sleeps only a couple hours every day and a half or so, which leaves him enough time to churn out books and still be active in raising the kids. As of the time of writing, he's got 4 teenagers, so it is pretty hectic, what with the mood swings and homework and skills to be learned. I guess things would go around somehow even without mixology and chemistry, but they sure help.
(Don't try this in real life, kids.)