SEO for your forum can pose a great challenge. We cannot ignore the SEO for our forum hoping that just by installing the forum script we can get the required traffic, ranking and clicks automatically. If you want to maximize the potential of your forum, then it is important that you optimize your forum too as you would optimize your website. There are some special points to note when it comes to forum optimization.
The nature of the forums are such that there is lot of room for duplicate content. We will have a number of links which have different linking text but the linking pages will be the same. For example, link text such as quotes, reply etc will lead to the same page. This can confuse the search engine bots. When search engine bots enter the same page through different links, it will consider that you have the same content in multiple pages. This can put you through duplicate content issues.
Make sure that you also use Robot.txt effectively to avoid search engine bots from reading unnecessary pages. When search engines find excessive content that are not related to your forum or your site, it will not be able to judge properly the essence of your website. This will affect the effectiveness of the keywords by diluting the keyword rich forum text with other content that are not relevant to the discussion or the site’s content. Pages such as user profiles, membership details etc., should be blocked from the search engines.
You can customize your script to incorporate meta tags including title tag as well as meta description tag. You can allow a certain number of characters in your post as meta description and write posts bearing in mind the head tag customization.
Though search engine bots can easily crawl tables, it may help to get rid of some of the tables so that the file size reduces with unwanted site architecture.
Also try to keep your header clean do not allow your CSS to eat up hundreds of lines. This will help the search engine bots to access the text easily and index the important content quickly rather than plough through hundreds of lines that are no way helpful on SEO counts.
Since your forum will be regularly updated, it should be frequently visited by the search engine bots. So get your sitemap ready as this is the only way to get search engines visit you frequently. Google has its own XML Sitemap; make use of this feature and get your site frequently crawled. Do not ignore pages with old discussion threads. Provide easy access to these pages. As long as these discussions are something to do with your site, they are useful.