As a Realtor and Professional Home Stager, here are a few of my thoughts. When you are selling a vacant home, it can often be a major benefit to add some furniture and decor to your vacant home because it allows the buyers to see what it would look like lived in, as well as feature the home's best features. If you go ahead and allow a tenant to stay in your home WHILE you continue to market it, it can have the opposite effect if the tenants are messy and/or hard to work with regarding showings.
However, if you are considering leasing INSTEAD of selling, it could be a good option if you use a reputable property management company. A good tenant can keep up with your home while basically paying for your mortgage until you are ready to sell. And at the $400,000 price point, I'd expect that price range of tenants would respect and take care of your home!