Changing PHP parameters when you don't have access to php.ini

If you need to change a PHP parameter but you can't change the system-wide php.ini file, you can achieve the same result by editing the appropriate .htaccess file, like this example:

php_flag register_globals off

Here's a link that explains it in details:
How to change PHP parameters when you don't have access to php.ini

Validating your site

Why is site code validation important ?

* mostly consistent display for your sites with many browsers (which display the one and same - unvalid - page very differently) and making your site more readable for different user agents
* helping exposing and repairing barriers to accessibility
* encouraging compliance with existing accessibility guidelines
* making websites accessible to all individuals, including those with disabilities
* demonstrating professional coding skills

For HTML / XHTML / WML / XML / RSS / ATOM / Google Sitemap: http://www.validome.org/
Validome allows Web Publishers to check their syntax with a reliable, high-speed validation service, in accordance to current official Standards. Valid code is very helpful, in order to avoid problems with different browsers and releases. A simple visual check of your site does not conform any more to modern webdesign and generally accepted technical requirements.

For CSS:
http://jigsaw.w3.org/css-validator/
W3C CSS Validation Service; a free service that checks Cascading Style Sheets (CSS) in (X)HTML documents or standalone for conformance to W3C recommendations.

Accessibility:
http://webxact.watchfire.com/
WebXACT is a free online service that lets you test single pages of web content for quality, accessibility, and privacy issues.