Possible Duplicate:
What are the best ways to increase your site's position in Google?

One of the most basic SEO techiniques is including accurate description below 64 characters in the tags of each page. I was wondering if is considered ethical SEO to set up the contents based on a search keyword for example. So if the user searches for 'apples pictures' for example, then the title of the webpage would be 'apple pictures'. Note that the search keywords accurately describe my website contents because the title will always relate to the body of the webpage and 85-90% of the terms searched for will return corresponding results. Is this considered a good seo practice and is it ethical?

Also, can someone explain what the idea is behind "linking"? I read somewhere that it is a good seo practice to link other websites and it is good when other websites link you. Does this mean that I should include as many links to other websites as possible (that are somehow relevant to my websites goal), also if I joined forums/services and posted my website url in the signature, would that still be considered other websites linking me?