If your 24-year-old artist still shows no interest in being an accountant, there's probably not much you can (or should) do to change her mind. Recognize that for some adults, a lower paying job such as waiting tables or working in retail provides the benefit of flexible hours along with the mental "space" in which to pursue creative interests or other passions. Just be sure your adult children understand the importance of benefits such as health insurance and retirement plans, and encourage them to seek out employers that offer those perks.
Many things have likely changed since your last job hunt, so no matter how pure your intentions, try not to be the overbearing parent with all the answers. And this part should probably go without saying, but always leave the actual interviewing and follow-up to the job hunter. No going along for moral support or calling potential employers to see if your superstar landed the job, like the "helicopter parents" we've read about who do just that for their "boomerang" kids.
Remember that you raised your children to make good choices; now empower them to do just that while you sit back and admire the results of all your hard work. We know it's a challenge to find the right balance between being too involved and not involved enough in your adult children's career endeavors, but you will be a better parent for trying.