Every stay booked through a listing site pays its fee. A guest who comes back, or finds you by name, can book on your own site instead - and you keep the relationship, their email, and more of the money.
They will if it looks cared for: real photos, the reviews guests have left you, clear house rules, and a person to write to. Linking to your listings' reviews helps, too.
Start with the guests you already have: a card in the house with your site's address, a QR code on the fridge, and a note after each stay. Returning guests are the easiest direct bookings there are.
Half Dome Hideaway, a cabin near Yosemite, has a site of its own - its photos, guests' reviews, things to do nearby and its calendar. Vacation rental sites come with the same pieces, booking and payment included.
Give us your website's address and we'll rebuild its home page, free, with a short report on what it's missing.