Next up, you need to use the home office regularly. And again, this doesn't mean that you regularly walk into the room, practice your signature with a nice fountain pen for ten minutes and then walk out. You do need to use the room consistently for business.
Now, this doesn't mean that you must use the room every weekday for huge chunks of time. Say you have a part-time gig writing a newsletter detailing changes or updates in your trade. If you spend every Saturday using the office to write the newsletter, you're still golden.
Just remember that the exclusive use rule still applies: You and your family shouldn't really be spending lots of time hanging out in the office for recreation. Even if you're only using your office one day a week for work, be wary trying to claim a deduction if it's packed to the gills with pinball machines and miniature golf greens for nonbusiness days.