SEO has two parts on page and off page optimization. If you know on page optimization it is very important to learn off page optimization also. Off page optimization is the last effort of your site, but it wants a good on page optimization. You’re off page optimization only works when your site has well on page optimized.
The off page optimization directly related to web site promotion, here are so many things in off page. Optimization is any site is easy but very risky also because a wrong promotion may harm your site. SEO has so many promotion channels by this we can promote our site in search engines. Article submission is one of the best channels, if you are doing article submission always read the submission guidelines. Some web masters believe in more submissions but it is the bad habit, always try to submit articles in good site (greater than 3 PR). It is the common practice that some people use one article more many sites but I think best way to put one article in only one site. Always use notepad document before submitting it on directory because your word wrap must be uncheck.
Directory submission is also a very good way of promotion, but now Google no more support of this channel. But we can do some submissions in good PR directories. Directory submission always creates effect on the site if you include the right Meta Tags and related Meta description of your site. Forum signature and blog commenting both are very good channels, both channels basically used for more traffic on your web site. But user forum user must contain good posts, never be spam in forums because it directly effect on your site. Blog commenting always beneficial for the site, but the blog in which you are trying to give comment must be related to your site. Blog comments not includes more fields, only one name field is require and your comment. Try to use your keyword in the name field it gives surely backlink to your site and increase the traffic of your site.
These are some good SEO channels, if you are starting off page optimization keep all things in mind. You will get good ranking by these ways.