Practices for Achieving POSH:

Avoid using tags for display instead of meaning.
Avoid use of <b> for making things bold; use <strong> or <em> instead.
Avoid use of <br> to create space between elements or paragraphs; use
<br> only for forced line breaks with paragraphs, for example, with lines
of poetry.
Use semantic id and class values that speak to their function, not their
display.
Stop using tables for layout; use them only for tabular data.
 Use as little HTML as possible to get the job done.
Avoid using more <div>s on the page than necessary.
Validate your HTML with an approved validator (see the Resources
section).