You're going to have to be more specific.
If your niche is very specific or non-competitive (and I mean very) all you'll need is on-page SEO and you'll have targeted traffic.
You could start a Facebook page. Post on relevant pages, etc... (the whole FB fan-getting process, read about it if you must) to get target fans which you can publicize a link to your website to.
More details are needed.
Hope what I said helps to some extent regardless.