Write a good and unique content and have a useful 404 page. Now what does it mean to have a useful 404 page on your website? okay so let's have an example of it, whenever a user search for a page that your site is not having then the server return a 404 error page but what happens is your visitor gets off from your site when he is redirected to a 404 error page by the server so let it not to be happened we do is what? we make a "404 page not found" page. SO now, if a user search for a page that we are not having on our website then this 404 page (created by us) comes into play. now the visitor will not see the server's 404 error but he/she will see the "404 page not found" webpage on our site having the links that say "back to the previous page". So by doing this what happens we don't loose our traffic because visitor never left our site. so i suggest you to have 404 error page on your website and make it attractive, search google for more ideas.