Put a lot of creative effort into your content and design.
Anticipate the interests of your audience. Look into what users might want when they come to your site for a two or three or four word query. Imagine a range of users. Anticipate vocabulary. Imagine possible searcher intentions.
If you're selling a product, ask yourself what users want to know about it before they buy, during the sale, after they buy. Ask others as well. Do research. Look at buying cycles. Talk to experts and new users. Test.
Are you providing channels for customers to get answers after they encounter some difficulties? If they have a great experience, is there some way for them to share that with others in a way that works for your niche?
If you're offering information, how can you present it in a fresh and interesting way? How can you make information easy to find and read or see on your site? How can you make difficult information understandable while not boring the experts?
What will keep users totally engaged with your site? Is it range and depth of content? Is it an app or interactivity? Is it really good videos? Fast page loads? Is it writing style? Is it the absence of junk pages and fluff? Is it respect for your audience? Perhaps it's a combination.
What will make visitors return? Fresh information? New products? Ongoing basic goods and services? Community? You want a site that's special enough in its niche for visitors to bookmark, recommend to their friends, and link to.
And chances are that it will need to work on mobile devices too.