In a profitable niche, what other ways to increase ranking?

I'm in a profitable niche right now. Manage to get $420 few days ago in just one day; and yesterday about $200.

The problem is... my site is ranked on the 4th or 5th position. I believe I could get even more leads if I'm on the first position.
What other ways (whitehat backlinking) can I do to increase my position?

Does Linkwheel really work? I've heard of reports that people got sandboxed after using it.

Linkwheels work well if done properly. Make sure you update the content on each part of the wheel often if you want to keep it effective. Integrate article marketing, social bookmarking, and rss submission within the linkwheel to make it more powerful. Everyday build a steady number of backlinks to your page and your ranking will increase over time.

You can also get traffic if you submit your RRS feed to directory or sumbit your site to directory. But I think you already have done that. In a post a have make people from BHW tell to me that buying traffic help a little bit (alexa ranking)

Try .edu links
Thread here http://www.blackhatworld.com/blackhat-seo/link-building/81007-share-your-edu-links-here.html