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look at other websites that have achieved this goal that you wish to do. you are going to start marketing agency and you want to know how to do the keyword research. Alexa.com compete.com they both feature information on sites other than your own. You can Google similar sites as well. A excellent example of a local SEO site that has succeeded would be whitespark.ca for B2B organic search look at any HubSpot partner http://www.impactbnd.com/ or http://www.kunocreative.com/ everyone these companies are doing well and I list them just so you can try and learn from what they have achieved. Case studies on B2B organic agencies are plentiful at http://www.hubspot.com/partners I hope this helps, Thomas