Off page optimization is a generic term for link building. Link building is a way of telling the spiders that you've gained acceptance as an authority in your industry or niche market. The more authoritative power you can gain the higher you'll rank in SERP's for keyword terms that you are targeting. Although controlling how your links are published on other sites may not be practical, by understanding what the search engines are looking for, you can optimize those opportunities when you do have control.

Search engines evaluate pages that link to you by the relevance of the linked pages. Having a link from a page on a jewelry discussion site will be stronger to another jewelry site than a link from "Bill's Home Page, We'll link to anybody!". In addition to relevance, search engines will gravitate to topically rich sites simply because they want to serve results that actually match a persons search terms, go figure!

Maximize Link Value

Every back link has a certain value but some links are much stronger than others. When soliciting links from link partners (reciprocal or traded links), directories, article sites, press release points, or other venues, you should keep in mind to:

Always link to your home page by using your domain name root. Link to mydomain.com, do not link to mydomain/index.php. This doesn't apply when linking to sub pages. Maintain consistency by using the www. Prefix in the URL. 

A note about this; You should edit your .htaccess file to do a 301 redirect from your root domain to www.mydomain This will give link credit for both your root and the www instances of your domain.

Use your keyword phrases in the anchor text for all links whenever possible. You probablt won't have control over 3rd party links to your site, but you can control the anchor text for all links within your site and from any 3rd party links that you can define such as directory listings.

Link Building
With a new site, it can be helpful to engage in a link building campaign to get your site some immediate exposure. As your site matures and develops more content, you will find that other sites will start linking to it without solicitations.

There are several avenues you can use to expand your link building campaign:

• Free Directories - Search engines use these human edited directories to find and categorize websites. Be sure you submit your site(s) to the highest trafficed directories possible. Getting listed in directories that target your niche is also important. Free directories such as DMOZ, Dogpile, Jayde and Zoom are a good start.
• Use our lists of PHPLinkDirectory, PHPDirectory and ESyndicat directories to get a head start on link building. When applying to directories, follow their instructions and make it as easy as possible for their editors to approve your submission(s). Make sure to use the title and description of your site to its full ability. Dont put HOME, WELCOME TO MY SITE, INDEX or just the URL as a title. Editors want relative content and if your listing says nothing about your website, well, don't expect to be listed anytime soon.
• Press Release and Article Sites - Many websites will be happy to publish a press release or content article and include a link back to your site. These sites can create an unusually high amount of traffic if you take the time to create good, thoughtful, and well written posts.
• Niche Industry Sites  - Many organizations offer free directories to their members with links to their websites.
• Forums and Discussion Boards (BBS) - Many forums allow you to place URL's within your signature cards. Avoid spamming forums and discussion sites because not only will you get banned but you'll also send out a bad image that is counter productive to your SEO efforts.
• Set up an affiliate program - Offer commissions on sales of your product(s) for those who will advertise your offerings and link to your site.
• RSS news feeds - publish company news though RSS syndication. Other websites pick up the RSS feed and publish your news story (which can include a link back to your site, of course).
• Paid advertising - While paying for back links isn't something I gravitate towards it does make sense in some cases. Make sure you have control of layout and link naming when purchasing back link placements.

Reciprocal Links
Also known as trading links, use the search engines to find websites within your industry that might link to you. Use your competitors back links to find more sites that may be willing to trade links with you. Visit those sites and try to determine who you should contact and send them a personalized e-mail introducing them to your site. Request consideration for a listing on their links page (and include the URL for that page) where your website would be of value to their audience.

Many owners/managers/webmasters will be happy to link to your site if it contains useful information that is directed towards their audience. If their site is useful for visitors to your site, you should consider reciprocating links. You should always avoid trading links with websites that have no topical connection to your site. When you solicit a link from another site, be sure to format your requested link to conform to the format published on the target link page. Be sure to use your keyphrases whenever descriptions are published next to links.

As you generate backlinks with keyword rich anchor text or from related authoritative sites, you will be maximizing your off page optimizations.