I was just having a browse on this topic, noticed the discussion on going upwind and I thought i'd just add to salty's suggestion of going to a cable park.
When I started kiting it was painful but I had the very useful advantage of having spent a lot of time wakeboarding or at a cable park. Sorting out the kite is hard enough, without having to learn how to ride a board while doing it.
Having the board skills made going upwind possible within 2-3 sessions once id worked out how to use the kite basically.
My take on it was, and still is, if you want to go upwind, edge as hard as the kite will allow. ie edge too hard with insufficient power, and you'll just slow down to a point where the board will stop planing. if you feel this happening, point the board downwind a bit, get your speed up and then try again, but edge a bit less. if the wind is insufficient, you'll have to work the kite or go slightly downwind to keep your speed up. if the wind is too strong it will pull you downwind! There may be some other things in there like where the kite sits in the window when edging too hard etc but my understanding isnt that great.
if the wind is strong enough, just park the kite at 45deg and edge. if its too strong, holding it up closer to 12 o'clock lessens the pull downwind, but has the side effect of lifting you off the water, potentially hindering your board's effectiveness.
Spending time at a cable park gives you the chance to practice basic board skills but also edging, and edging hard both ways! Nail that basic skill and you'll be upwind in no time, its just understanding the relationship between the kite's power and the board's drag when edging/going downwind.
Just my take on it. Im still pretty new so some of that might not be great advice, but its how it seemed to work in my mind when I got the hang of it.. Obviously useless advice for anyone who doesnt have a cable park nearby! In that case, time under the kite is all you have!