Here's something that might work:
1/ Don't miss the flight. Sounds stupid but I had a guy
who missed his flt to Maui via YVR because he wasn't paying attention...he was sitting across from the gate....20 ft away!
2/ When you see the gate agent arrive, go up to them and tell then how this is the first time your on a big plane. Tell them you're a little nervous about flying, but excited at the same time. Tell them how much you like planes. In the middle of it all, ask them if you'll be able to see alot out of the window seat you're in. Maybe, just maybe the agent will give you a better seat ----- read "upgrade". I've seen it work before...let me know if it works for you.
P.S Never ever ask for an upgrade...act stupid and let them do the work.