You can use the 2 scores approach, as described in the last answer I made here: Re: Emails Opened vs. Emails Delivered - By Lead
Or the report described in this same post.
But at the end of the day, all of this will not be totally accurate, as the "Open" score will fire twice if someone opens the same email twice.
Marketo is better at counting the number of time a lead opens an email than counting the number of emails a lead has opened
This inspired me this idea: Add a "first time" constraint to "opens email" and "clicks link in email" triggers and "email opened" and "click link in email" filters, as well as to "Visits web page" trigger and "visited web page" filter
Thank you Greg! I greatly appreciate your advisement on this topic. I look forward to trying out your suggestions