How to set up free, open source analytics in under 5 minutes

I made this mistake and am now starting to see tangible correlation between the tactics I'm using to grow my business and traffic / conversion on my site.

If it can't be measured, it can't be improved. How are you tracking your results?

Check out this guide to installing free analytics on your site.

Do you have any other tips or experience with analytics? Have you found it helpful or a massive pain?