There are many features which can help you to optimise your site, all of which come as standard without the need for extra modules or hard-coding.
You can tweak the meta data for a website page, a news article, a product category or a product:
Title (usually the product title, news title or page title)
Keywords (separated by a comma)
Description (separate from the summary)
When you create a page, product, or news article you can write in the body section too, allowing full control over your content to balance your meta data with keyword density.

You can set default meta tags (see the SEO tab in Core Settings). These will be used on the home page, or on a page which you have not yet set specific meta tag information.
Pixel Cart has an option to generate search engine friendly URL's, this option is enabled by default upon installation. The lesser levels are to avoid any complications due to server limitations.
There is also a robots.txt file in the root folder, which you can adjust as you see fit.