You want to find job seekers who will thrive in your company culture. Use your ad to paint a picture of employee life.
What is paid time off like? Is the role remote or hybrid? (Be honest!) List any cultural aspects and perks you offer.
Sometimes by recycling old postings, you can unintentionally tell a candidate they're not a good fit for you.
Are you using gendered language in your titles, like "chairman" instead of "chairperson"?
If you find yourself looking for a "ninja" or a "rockstar": 2010 would like its job listing back, and employees may see this as a toxic startup red flag.
Don't exhaustively list every single task your candidate will do! You should only list key responsibilities and expectations.
By putting every little task in your listing, you may signal the job is tedious, or alternately that you're trying to hire one person for three jobs.
Good employees want to know they'll be appropriately compensated. Don't waste their time (and yours!) by going through an interview process without discussing salary.
And never mind wasted time: it's the law in several US states now that you MUST list a salary range.
In the age of one click apply, it's easy to apply to a hundred jobs in an hour that a candidate may not be a good fit for. Ask clear screening questions to help you filter.
On the flip side, don't ask for incredibly onerous tasks, like writing an essay about the company or pitching their great marketing plan. Good candidates may weed themselves out if it requires too much effort to apply.
Rather than sifting through each resume by hand, use a resume parser to help you find the keywords you're looking for.
A good Applicant Tracking System (ATS) will also help you deal with the large quantities of applicants out there.