Just wanted to finish SEO checklist with this final part 3. These are just absolute basics but crucial basics of SEO.

11. Avoid using frames

Some SEO “gurus” say that frames are horrible for SEO, some say they are just not the best choice. In any case, you probably don’t want to use frames unless you really have to or have pages that don’t need good placement in SE. Search engine Crawlers will have trouble getting through to the real content and effectively indexing individual pages. Also, most functionality that the use of frames allows is easily duplicated using proper CSS coding. There is still some use for a frames-based web-page layout, but it is just better to avoid it if possible.

12. Making sure that your server is returning a 404 error code

You’ve all seen it. You’re browsing around at a new or familiar site, clicking links and reading content, when all of a sudden you get that blank screen that reads “404 page not found” error. While broken links that point to these pages should definitely be avoided they say that you also don’t want to create a “custom error page” to replace this page. And here’s the explanation why; if you generate a custom error page, crawlers can spend time following broken links that they won’t know are broken. A standard 404 error page is easily recognizable, and search engine crawlers are programmed to stop following links that generate this page. If crawlers end up in a section of your site that is down through an old link that you missed, they might not spend the time indexing important parts of your website.

13. Ensure that crawlers don’t fall into infinite loops of scripts

Many webmasters will include scripting languages, such as Perl, Php and Asp to add interactive functionality to their web pages. Whether for a calendar system, a forum, eCommerce functionality for an on-line store, etc. scripting is used quite frequently on the Internet. However, what some webmasters don’t realize is that unless they use robots.txt files or take other preventative measures search engine crawlers can fall into what are called “infinite loops” in their pages. Imagine, if you will, a script that allows a webmaster to add a calendar to one of his pages. Now, any good programmer should base this script on calculations - it would auto-generate each page based on the previous month and a formula to determine how the days and dates would fall. That script, depending on sophistication, could plausibly extend infinitely into the past or future. Now think of the way a crawler works - it follows links, indexes what it finds, and follows more links. What’s to stop a crawler from clicking “next month” in a calendar script an infinite number of times? Nothing - well, almost nothing. Crawlers are well-built programs that need to run efficiently. As such they are built to recognize when they’ve run into an “infinite loop” situation like this, and they will simply stop indexing pages at a site that is flagged for this error.

So preatty much the simpler the page, the better and easier for Search Engines to index your pages even though crawlers are getting more and more sophisticated every day. Just keep this things in mind when building your site and optimizing your pages for Search Engines.
This will conclude Crucial SEO checklist with this part 3 .

You can read part 1 here: Crucial SEO Checklist Part 1

You can read part 2 here: Crucial SEO Checklist Part 2

Enjoy.