I'd go with super high energy - you're gonna have to be pretty full on to top some of dem dere fresher kids! Run up to them, ask if they're freshers and high five the sh1t out of them lol.

TBF though mate, everyone has their guard down during freshers week - they all want to meet new people. You could probably walk up to any group and introduce yourself and they'd be more than happy to chat to you.