Hey BClendening:
First, I wore a size medium Twin Jet but I wear a size XL Jet fin with XL spring straps (I wear a size 9.5-10).
Now excellent tips from above, and I want to comment about Sloth's comment, "No reason you cant watch a ton of videos online and get a feel for donating the long hose, figure out trim position, and figure out fin techniques. From now and until you do fundies focus on buoyancy, trim, manipulating the long hose, frog kicking and most importantly buddy awareness. Buddy/situational awareness is probably the most critical skill to have so start focusing on it early".
This is how I started last year. I read all I could, watched videos galore, searched all that was GUE [and DIR], and then dived dived dived. I thought I had it pretty much down until I got an invite from SparticleBrane to meet him at a local quarry. Wow. Despite me having more dives than him, he was obviously a better diver than I was. I was so amazed how he could hover in the water column like he was a statue on land. His movements were crisp and with purpose, and his buddy awareness was like no other. That is what I wanted to be like. I actually stopped diving after we met because I knew that no matter how hard I tried, I could not fix my deficiencies without more watchful eying (and SparticleBrane had his own (AND BIGGER) sticks in the fire). Seeing how it was supposed to be done in person was a big help and just another reason for me to go to class (and the time from diving with SB to class was relatively short). I obviously couldn't pick it all up from video and reading but it was a start.
Finally, despite the route that you take, keep in mind that GUE-F has nitrox incorporated into the class. I dunno if it's worth it to you to spend for a strictly nitrox class if you are going to get it again (assuming you go the GUE route- I can't comment about UTD). On the other hand, it could be viewed as reinforcement to your initial class.
I hope this helps and good luck with your classes.
With kind regards,
Thomas