With the new school year just around the corner, companies are actively recruiting and reviewing candidates to build a new troupe of interns for the fall semester. And for good reason! Intern programs -- when built right -- are a great way to get additional support for your marketing team, and teach your interns the ins and outs of contributing to a business.  I started building HubSpot's intern training program two years ago, and since, we've hired approximately 33% of our interns as full-time employees! I'm very passionate about mentoring talent and setting young marketers up for success, so to help you build a top-notch marketing internship program, check out the following guidelines HubSpot uses for our own intern program.…