Google Tag Manager/Analytics

I am trying to set up the simplest and most effective analytics management for website, e-commerce, and email. I use Mailchimp for email and have just set up a new Google Tag Manager (GTM) account, linking it to Vin65 by following the instructions here.

I’d like to know how to use GTM/Analytics to first access our data and then use it to better tailor our website. Are there any discussions already happening or good reference guides that anyone can refer me to on how best to setup and manage this?