Depends if you have more time or money!

If you have more time then money go about doing it yourself and learn the ropes.

If you have money and want to focus on other aspects of your business get a SEO to help you. There are some good ones on Odesk but do your research first!

I wouldnt trust $5 seo services but thats just me!

You have quite a few options. Do them all yourself, do some yourself, do none yourself, incorporating outsourcing via sites like oDesk or Elance, or, what I'd suggest, using services here on WF.

In the beginning I always recommend doing the grunt work yourself. That gives you a better understanding of how SEO works, what to look for, and thus you can set expectations with your outsourcers.

If you haven't had the experience in SEO it can be difficult to judge the effectiveness of what your doing and it can also be difficult to set the expectations with your team.

I always recommended oDesk.com because its ensure you get the work. And Yes, I use White Hat Technique to get best SEO result.