Marketing attribution/ ROI

Marketing attribution/ ROI

Dear community,

We're now starting to figure out a way of measuring the impact of all our marketing activities against the amount of the won deals in CRM, using CRM functionalities. 

I know this is a difficult topic. Rough ideas would be a system of touchpoints to determine which activities influenced the most for a deal to be won but we're a bit in the dark here. 

Any ideas about where to head from here? 

Thanks in advance.