Keep it real - go enough distance to get you home safely and enough speed to get home at the time you need to be home.

After that, I would say distance. Speed will come.

Have fun. Learn to handle the bike. Learn to shift. Keep the pedals turning. Learn what your comfortable pace is. Can you turn 6 minute miles? 5? 4? Learn when wind resistance starts to slow you down.

Learn how your body works. Notice how your different energy systems ramp up and down as evidenced by things like heart rate, breathing, and cramping. Learn how fast you recover.

Have more fun. Wear out some bike parts - grips, a chain, tires. Learn to replace them. Calibrate your calorie intake to your riding.

The number one thing at this level is simply racking up a couple of thousand miles - however you get it done.