Marketing in CRM - How do i get the most bang for my buck?

Hi everyone, 

For a long time, we've been neglecting the marketing functionality in CRM. In each of your opinions, what are some of the best features of the marketing module and each of its components (templates, campaigns, etc...) and how are some of your tips to get the most of out of the product? 

Some simple how-tos for typically unused features would be great as well!

Thanks for your input!

Kimberly