You could do either, but realistically you cannot be an SEO consultant if you don't know how to do SEO or rank a webpage can you?

But, lacking any such skill what you could do is to get and then sell leads to a professional SEO, while learning it yourself.

Learn SEO first. Try to rank for any small blog of yours and then go big. SEO is not only bookish knowledge it is practical experience based mostly.
The more you will play to rank for any site the more you will learn and gain experience. Once, you have ranked quite a number of blogs that also doesn't mean that you have gained enough knowledge. The most basic thing about SEO is that its always changing. So, you will have to keep updated yourself also.

You can be a good SEO consultant. You just need to learn some basics about SEO. Just learn about on-page SEO and off-page SEO like social bookmarking, social network profiling, forums, question and answer, infographics, web 2.0, edu-blog posting, etc.

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For becoming an SEO Consultant you have to enhance your SEO skills first and you have to have some years of experience in SEO, so, join SEO courses and or Interns and work on live projects under the Guidance of your mentor and ask your queries if you will face any, but first try to solve that your self.
If you want to do it your self, then build a blog for practicing. The theme your bog should be based on your interest so you can update that daily or within 2 or three days because practical knowledge is more important than theoretical knowledge. Join Forums and follow the popular blogs of experts and also watch the online videos on you tube.