This topic is far more expansive than a single set of campaigns: it requires an understanding of available SEM attribution models and an educated choice about which one(s) to use, taking into account implementation/reporting hurdles in Marketo.
If you want to tactically track last touch for this particular case, add hidden field(s) to a form that grabs UTM params and manage program membership + success accordingly in Smart Campaigns. But realize that Marketo is not the place to analyze anonymous visitors while they are still anonymous. Upon conversion, you'll have full access to their once-anonymous activity history, but for still-anonymous reporting you want to use 3rd-party web analytics (I am a fan of Clicky, but the obvious default for most people is GA) or specialized apps like Path to Scale, Bizible and the like.
The advanced/strategic decisions you need to make will take analysis and education. I recommend you graze over the many Community threads and blog posts on this topic: many are written by experts in the discipline and a short engagement with them will pay for itself many times over.
Thanks for your quick response.
But again i am not able to connect the dots here. I understand we cannot work on anonymous data so lets say 100 contacts has submitted the marketo form which we want to know how many we got from SEM campaigns.
We are using UTM tracking and we can see the results in GA but we cant have the user information, our goal is how to capture them in Marketo.
If you can elaborate the process it would be great.
You can read Allison's approach here: https://nation.marketo.com/message/96605 -- one of several workable tactical approaches you can follow (again, picking up tactics here and there is not a substitute for thinking through your attribution model).
Note she reads the page's query string directly to determine source info, rather than using a hidden intermediate field. I am in the habit of using a field rather than relying on string matching in a flow, since multitouch attribution always needs JS + cookies + hidden form fields anyway.
Thanks Sanford, this article was helpful.