BizSugar.com › Success Stories › Talking Web Analytics with Umesh Choori of Network Solutions

Top 5 things really depend on the business and situation you are trying to address. I will try to keep it more generic and broad.

Implement analytics on your site, even if it is basic site. If you are budget constrained, there are relatively functional web analytics tools in market for free. So no excuse to not to do it.
Understand where traffic is coming from – by geography, campaigns, paid search, natural search, referring domains etc…
Measure conversion rate (whatever you want the site to do i.e. sales, sign ups, lead generation forms, calls etc.)
Identify the most visited pages, and continue to improve the pages through testing (alright, this may cost in infrastructure and resources, however it is worth it, would not you train your Sales representative?)
Identify the website paths (series of pages) that drive your conversions. Improve these paths to provide better visitor experience while achieving your business goals.