The Google UTM Builder is a great tool for tracking traffic to a website. Track your Adwords campaigns, email click-throughs, coupon pages, you can even track offline marketing with vanity URLs.
Below is an example of how I set the parameters for a dynamic inventory campaign.
google-aw = Google Adwords
ppc = Pay Per Click
dyn = Dynamic
all - for all vehicles (may want to change that to new or used later)
base - use this as a baseline for future iterations
To create your own tracking URL, use the Google UTM Builder tool. Decide what values to use based on the type of campaign you are planning to run. The more information the better.