Automate lead source field update

[Anonymous]

Hey guys,

Trying to automate lead source field update for the leads coming through Marketo forms. Our sources are: Direct traffic, organic search, FB ads, Linkedin ads, Adroll, FB retargeting, referral website.
Think the best way would be to use querystrings, and to create a smart campaign for each querystring contained in the Original referrer: 
IF querystring contais "utm=LIads" -> update source to Linkedin ads
IF querystring contais "utm=FBads" -> source = Facebook ads
and so on...
Also if original referrer is blank,  -> update source to Direct Traffic

Would this rule cover all field update cases? Sometime the Original Referrer field shows just the landing page with the form, so it's not possible to find the source.

[Anonymous]

That's how I'm doing it; I have listener campaigns for UTM codes and update their field status.

[Anonymous]

This is how I do it. Of course thinking through all of those rules & tags are what is most important, but at a high level, this is what I do.