What are the BEST techniques for improving website conversion rates?

Make it interesting, informative, helpful, easy to navigate, to the point and use effective calls to action.

To be honest there is too much things you can do, at the first clean meta tags, clean code, split the page upon the used HTML Base using standard and known tags, compress the code html, css & js, compatibility with all browsers and at this time should be compatibility with mobile & table devices and to take it through the search engines clear sitemap and robots.txt help alote. i think this is the main issues.

Its quite debatable topic and hard to explain within limited words if you asked this to any UX designer they maybe give you list of100 points

In simple words Clean design and targeted content .