Well, you can
include cleaning tips, but make it sound like it takes a lot of work/time to do correctly, and be sure to include some sort of tag line along the lines of "If you'd rather spend your time doing fun stuff instead of cleaning, get in touch with us at (insert contact info or link to your "contact us" page)."
And if there are small things, too minor to come within the scope of your services that a homeowner/office manager could take care of for themselves, they're liable to appreciate your tips on how to accomplish these tasks more effectively. And when they need help with bigger cleaning jobs, who will they think of first?
Blogging is primarily for branding, developing awareness and positioning yourself as an industry thought leader. People who find you through your blog are probably too high in the sales funnel for a hard direct sales pitch to be effective.