Be aware that sitemap generators such as xml-sitemaps create a good listing but do not prioritise each one as you might - so have a look through the final output and ammend as required.
On optimisation, I understand that the major engines prioritise on
URL content
Meta Title
Meta Description
<h1>
Body Text
Recency
They also track link backs (links to your page from other sites) and click through rates.
You can check how well you're indexed by using Google wemaster tools which is free.
In addition, they used to use meta keywords, but from what I understand, this was being abused too much and is no longer used to the same degree.
The trouble is, if you can't get into the first few pages of your prefered search engine, it's difficult to raise through the ranks so try to concentrate on niche wording that is more specific to your site.
For instance, "Forum" would be lost in millions of other sites as would "Gaming Forum", but "Gaming Forum XBox360 RPG" would give you a better chance.
In addition, remember to use the "alt" and longdescription tags on your images - these get picked up on by image search engines.