Hi rob3786
When looking at any kind of online marketing, I would suggest that you rather look at the target audience first. Google groups are outside your target audience and the visitors you will receive will most probably not even convert.
SEO works on the same basic principle as you need to do keyword research and compile your pages with the primary keywords in mind. That way you get the best conversions for the traffic your site generate. You can apply the same rule on Banner advertising, viral marketing etc.
Alexandre mentions a few very important points.
SEO is your primary most important marketing method. Onpage factors are simple to apply and most probably has added benefits on the usability of your site. Address the
SEO issue first and keep on applying it as you continue growing the content on your site. It is simple rules that are easy to apply and then you can address other marketing methods as you go along. One of the points that Alexandre mention is Page titles. They are all the same. It is a simple process to make them unique to each page. It will at most take you a day or two to sort out and you will be amazed as the traffic increases.