I want to track the source for incoming leads, so we can connect sales to marketing efforts.
As an example:
google ad > landing page form fill > new contact in Marketo.
Assuming a new contact clicked a google ad, then filled out the form on the resulting page, is there a way to show that in their marketo record?
I usually would look at their activity record and see what all was tracked and use that information to look for that action and then fill in the lead source.
I can usually see info on the webpage id in the query parameters. You could also look at using a hidden field for the source on the form fill.
This is where UTM parameters come in handy. You can use utm_campaign or utm_content (depending on your overall UTM strategy) to populate the value of your specific ad.
You would create a series of custom fields (ideally for FT, LT and MT attribution) and place them as hidden fields on your forms (to capture the URL parameter or cookie value). Lots of existing discussions on the community that describe this at length: https://nation.marketo.com/search.jspa?q=utm%20tracking
You might also be interested in Justin Norris' latest blog post on attribution: Marketing Attribution: What It Is and How It Works