jms said..
Anything post 2010 should be a more modern design with more modern safety features.
I'd rather go for 2015 new than 2016 used (depending on the model). The new kite won't have any wear, and design changes over one year shouldn't make a big difference.
You'll want a beginner friendly kite - a surf kite or allrounder. These are easier to control and relaunch than a high aspect race kite or a wakestyle kite.
If buying second hand make sure the kite holds air, is symetrical when pumped up, and check for stitching/repairs on the canopy. Repairs aren't that bad, but an unrepaired kite is for sure worth more than a repaired one. Also check to see if the repairs look like wear and tear or from an accident. Wear and tear is a bad sign as it's likely to recur/spread where as an accident is a one off. For example, one of my kites has been getting holes where the canopy sits against the leading edge on both sides = wear and tear = I've got a replacement kite and it's my spare now. Another kite has a few holes in the middle of the canopy from where I drifted into rocks, and that's not a show stopper.The school should give you advice as to a good size for your weight and location.
You took kitesurf lessons right? They're important!
Usually pin holes or wear on the canopy where it touches the leading edge is caused by sand being trapped between the two during pack up. If you don't rinse this out before your next session, sand stays there next time you pump up and wears through the canopy while you're flying. Usually a sure sign of a kite that wasn't cared for properly.