HTML headings and emphasis tags are the most basic forms to indicate important content.

Tips:
1. use your keywords in the headings and make sure the first level heading (<H1>) includes the most important keywords.
2. never duplicate the title tag content in the heading tags.
3. for more effective SEO, use only one <H1> tag per page

Declare the language in use can help search engine to better understand and rendering your page, especially when special characters are encountered.

Declare the character encoding can help search engine to better rendering your page, especially when it comes to
non-asii characters.

Robots.txt file can be used to regulate access of search engine crawlers, properly configured robots.txt file can help
crawlers to better understand your website.

Tips:
1. grand robots access to those pages you wish them to crawl.
2. restrict access to those pages you do not wish search engines to see and crawl.

Sitemap helps search engine crawler to identify your website pages.

Tips:
1. ensure all your important pages are listed in the sitemap.
2. ensure to indicate the frequency of change and importance of each url.
3. inform search engines of the location/URL of your sitemap (eg, For Google, you can set the website sitemap location through Google Webmaster management panel).

Flash content can not be properly indexed by search engines, and normally flash file is large in size, which slow down the loading of your page.

Tips:
1. avoid flash content whenever possible if you wish to have a fast and SEO friendly website.

Framesets and individual frames could cause problem for search engine to crawl your pages

Tips:
1. avoid frames whenever possible.
2. search engines do not like frames.
3. use iframe instead if you really have no choice.

nested tables could slow down page rendering and lead to bad user experience.

Tips:
1. avoiding <table> for your page layout.
2. using <div> instead of <table>.

Search Engines treat URLs with or without "www" as two different records.

Tips:
1. edit your .htaccess file and permanently redirect one to the other (eg redirect www.mysite.com to mysite.com).

Users are concerned about the safety of their online transactions. Trustworthiness rating is based on real user ratings and that tells you how much other users trust this site, so do the serch engines. note: this trustworthiness score is provided by WOT (Web of Trust).

Tips:
1. pay attention to the look and design of your site, many people look for visual cues when assessing a site`s credibility
2. make your site easy to use, sites that are easy to navigate are perceived as being more trustworthy.
3. make it easy for user to contact you, users will be more comfortable and feel more secured shall they need to get in touch with you.

Ensure that your site is malware free and does not cause harm to users` computers.

Tips:
1. do not put virus, malicious worms, adwares, trojans, spywares and suspicious phishing code in your server.
2. take suspicious behaviours seriously, have a regular check-up and monitor closely of your server`s log files.
3. if your site is black-listed by Google as suspicious, clean it up before requesting for a review.

Too many domains hosted on the same server is an indicator that you are not really serious about your website, and your site will have a higher chance to be surrounded by bad neighbours.

Tips:
1. the fewer domains hosted on the same server/ip the better.
2. avoid shared hosting whenever possible, especially when there are already hundreds or thousands of sites are hosted on the same server.
3. dedicated ip or resources for your site not only do good to your site visitors but also favoured by search engines.

A secure and safe server is not only good for your site visitors but also good for search engines.

Tips:
1. server software version information can be utilized by malicious visitors to attack your server.
2. by turning off the server signature, you actually have made your server a little bit more secure.
3. for Apache server - edit the apache2.conf or the .htaccess file to turn server signature off.

domain name choice and domain age are crucial for SEO.

Tips:
1. keep the domain name short and relevant to the content, which will be easier to be remembered and related to.
2. older domain tends to be more trustworthy.
3. register a domain for more than 1 year, and search engine will think it is a serious business.