Hello, this info intends to answer the most commonly asked questions related to SEO, especially from the angle of message boards. It is targetted at beginners, so if you're familiar with SEO you probably won't learn much from this. The info has 2 parts, a quick FAQ and some interesting links (basically a dump from my seo-realted bookmarks).
FAQ
What is PageRank?
PageRank is a score given by Google to each web page (not site) on a 0-10 logarithmic scale that is used as one (amongst many others) of the parameters for building the Search Engine Results Pages (SERPs). This score is calculated using an incremental mathematical agorithm.
Basically, at increment 0, each page starts with the same amount of pagerank. Then between each step, the new PR of each page is calculated depending on the amount of links to this page in google's index, on their respective PRs, and on the number of links on these pages. The algorithm eventually converges, which gives the PR one can see on the google toolbar.
The PR is used as an indicator of a site's importance. The more important (read, high PR) sites link to you, the higher your PR.
Note that PR is logarithmic, meaning that a link from a PR8 page will be equivalent for hundreds of PR3 links.
Note as well that PR is only one in many factors influencing your site's rankings, others including, on-page content, and inbound links anchor text. A high PR without a well-thought keyword strategy may not bring much traffic.
Note finally that the PR you see on the toolbar is updated only once in a while (it's generally a couple weeks/months out of date), and that it is rounded down (the number not changing does not mean your actual PR did not change).
What to do to improve my PageRank?
Get more links to your site! The more links you get, from pages with PR as high as possible, and with as less on-page links as possible, the higher your PR will get. Using the command link:www.yoursite.com in google will show you some of the sites linking to you (it is generally considered only sites with PR=4 are listed).
You can get links to your site by submitting it to directories (see below), exchanging links with other webmasters, or by generally having a quality site and promoting it a little bit so that people naturally link to you (whatever link exchange networks may say, this is the most efficient).
Why do I have PR0?
A page with PR0 is generally a page that has been recently added to the index. Google knows about it, it may show up in SERPs, but no PR shows up yet. Be patient!
The other possibility is you got banned from the index for black-hat SEOing (trying to manipulate the SERPs using non-conventional techniques), but it's unlikely you would be reading this info if it was the case .
Why do some links seem not to be counted?
As mentionned above, the link: command only shows backlinks with a Pr higher than 4. Also, links from sites using redirect scripts combined with robots.txt, form links, or javascripted links may not be counted by the search engines.
Why does googlebot only visit the home page?
This pattern is often seen for very new sites. Basically googlebot finds your home page, gives it PR0, gets back to it a few times, than it will give it a PR, go one level deeper in your site (giving PR0 to all newly found pages), and so on. The deepness of googlebot's crawl depends of your home page's PR. Get more links, and you will get more pages indexed as well. Again, be patient!
What to do to improve my rankings in search engines?
1. First, build content. Without content you won't go anywhere. For the special case of a forum, that means get members, activity, interesting discussions. You may think about adding content pages if your site is forum only.
2. Then the second step is to think about what searches you would like to rank high on. The keywords you will choose need to be relevant, and to be searched for (check out the resources section to see keyword popularity tools).
It's useless to rank well for an irrelevant term, or for a term that nobody searches.
Remember that the most searched terms are not necessarily the best ones for you though. They are much harder to perform well on, and sometimes not the best for your site (an ecommerce site selling mountainbikes should probably target "discount mountainbikes" or "buy mountainbikes" rather than "bikes").
3. Optimize your on-page content. You have built quality content, cool, now optimize it for the keywords you have chosen. Most importantly, your keywords should be present in your page title. While you can neglect the other meta tags, title is very important, both in the eyes of the rankings algorithm and in those of the user looking at the SERPs. The second important on-page factor is internal links. Anchor text of links to a page is one of the most important parameters in the rankings algorithm, so don't waste the fact that you can choose the anchor text of all your internal links. Of course you cannot choose your forum's topics title, but you can choose your home page and your various forums title and anchor text, so choose them wisely. Also, remove additional text in topic titles than just the title (like "powered by whatever forum software" and such).
4. Make sure your pages are indexable. Hide session IDs from robots, do not use javascript links, if your site has thousands of content pages, create a site map.
5. Build more content! Get your community growing!
6. Get links to your site. As much as possible, try to make those links have your keywords in their anchor text.
7. Get more links to your site.
8. Be patient.
Do i need to submit my site to search engines?
Not really, although that won't hurt. You won't rank well if you don't have links to your site, and you will be found if you do. So getting inbound links is the best submission you can do.
Where can I find people to exchange links with?
To be able to exchange links, you'll need a links section (obvious but well...). Go to sites related to your topic, and kindly introduce your site, why it is relevant to their own topic, then suggest a link exchange. You may be much more successful if you visit sites that don't have themselves a forum for their visitors to discuss. You may even offer them a dedicated area in your forum if they seem to get high traffic.
How to get more pages from my forum indexed?
Remove session IDs from URLs for guests (and therefore search engine robots), and do not require cookies to be enabled. I think most forum software I know of can achieve this through a mod/hack when it's not built in. This is the most important, if you leave SIDs robots won't get further than one or two levels.
If you have access to mod_rewrite, and a search-engine friendly URLs hack is available for your software, install it. Robots are getting better at indexing dynamic URLs, still they go much further and faster when the URLs look static.
Alternatively, an archive hack/mod may provide some results (although I'm not a big fan of it since it duplicates pages).
Have your forum readable by guests. Registration-only forums are not only bad for getting new members, they're also pretty bad for bringing search engine traffic to your site.
What should I not do for SEO?
Do not go to link farms, do not use blind link exchange services, do not use spam techniques (hidden text, cloaking pages etc.etc.), do not link to "bad neighbourhood" (pages using such techniques).
More generally, never do anything for SEO that will lower the quality of your users' experience.
Still not working, what can I do?
Be patient! It takes time to rank well for traffic terms. Not 2 days, not 2 weeks. On-page changes may take any time up to two months before being taken into account in the rankings algorithm (even if showing up in the cache before that), and sitewide changes may often take several months before you can see their actual effect.
Finally, don't forget that search engine marketing is only one way to promote your site. You can get a lot of visitors from links that are not good in search engines terms but great in traffic exposure (like forum signatures). Search engine marketing is certainly not in all cases the most efficient way to promote a forum. Having a great community and having your users let it know around them will probably bring you more traffic.
