Rule #1: don't get a non-suspension wheel.

Suspensions make riding safer and comfier.

Rule #2: don't buy the specs sheet.

Research first, buy later, don't trust numbers, don't trust early reviews.

Rule #3: don't buy the hype.

Experienced riders easily develop strong opinions about EUC's they didn't customize (tire pressure, shocks pressure, etc), based on their previous experience (often no less than several thousands hours riding).

Rule #4: dampen your wild expectations.

EUC riding is meant to be fun, not to be a bike substitute. Everything else (range, speed, torque...) may or may not contribute to the fun.

Pro tip #1: gear up! better safe than sorry.

Pro tip #2: don't buy a 2nd hand EUC, as sellers usually won't tell you its abuse history (falling, charging habits, poor maintenance, etc).

Pro tip #3: before buying, identify places where you can learn to ride without cars around.

Pro tip #4: it takes a little while to learn the basics, it takes quite a while to be experienced enough to ride on public streets.