#1 You must be strong
First of all, let me tell you that I am 5'4", female, I weigh 100 pounds, and I have only been to a gym once in my life. Even though my arm muscle is virtually non-existent, I can still manage to kiteboard hours straight because of the harness worn with kiteboarding.
#2 I'm too fat / too tall / too small / too old / too young
Many kiteboard stores require you to weigh at least 80 pounds in order to take a lesson. I've seen just about every size and shape out there kiteboarding even guys in the 300 pound range.
Height doesn't matter, but if you are a petite rider, consider buying a seat harness rather than a waist harness. This will move the bar closer to your body and put the power/depower strap within better reach.
I've seen plenty of guys in their 60s & 70s kiteboarding. If you have back problems, buy a seat harness rather than a waist harness, and buy a kite that has a lot of depower (bow, SLE, or hybrid kite).
#3 Kiteboarding is very dangerous
As long as you take the necessary pre-cautions, kiteboarding is relatively safe. I say relatively, because everything in life has risk, even driving your car to the grocery store. However, if you don't know what you're doing, things can go bad, very bad. Take a lesson! When in doubt, don't go out. Never ride by yourself. Don't kite in storms or other times when the wind isn't steady and reliable. And again, take a lesson (the more the better)!
#4 I don't need a lesson
Just because you're a pro wakeboarder/snowboarder, etc., doesn't mean you're a good kiteboarder. You need to learn how to fly the kite as well as learn how to setup the kite, relaunch, perform a self rescue, etc.
This is not wakeboarding, skiing, or surfing. It is more comparable to scuba diving, except if you screw up, not only are you putting yourself at risk, but also everyone on that beach. It is absolutely critical that you know what you are doing. A minimum of at least one lesson is mandatory. No exceptions.
#5 I'll take a lesson and be riding by the end of the day
Each year the gear is getting better and better. Three years ago, it would take weeks to be able to learn what people now learn in a matter of days. Even so, do not expect to be up and riding the first time (or second time for that matter). It does happen every now and then so to improve your chances spend as much time as you can with a trainer kite and work on your board skills.
#6 Trainer kite? I don't need a trainer kite!
Buying a trainer kite is one of the smartest moves you can make (along with taking lessons and buying the proper gear). You can learn so much with a trainer kite that by the time you take a lesson, you'll feel much more comfortable handling the real thing and your lesson will go much smoother. You can learn mandatory kite flying skills the hard way (with a powerful kite), or you can learn it the easy way (with a trainer kite); it's your choice.
#7 Kiteboarding is expensive
If you go out and buy the complete kiteboard set up (kite, bar & lines, harness, board), you're looking at around $1,500 - $2,000. Ok, that number may seem big, but let's think about this. If you want to wakeboard, you need a boat plus plan on spending a good chunk of money on gas each time you go out. In the winter time, you spend money on lift tickets every good powder day. Why not just strap your snowboard/skis on your feet and go snowkiting (use the same kite and harness, just add your skis/board). When you think of it that way, the $1,500 for year-round fun doesn't look so bad.
#8 Kiteboarding can only be done in the ocean
Wrong. Kiteboarding can be done in any large body of water. Heck, I've kiteboarded in a large mud pond that was only about a foot deep (not recommended). A sandy shoreline along with clean, steady wind is ideal. Open areas like the Great Lakes or oceans typically get smoother wind than inland spots like lakes and reservoirs. Kiteboarding can also be done in the winter time (snowkiting) on open fields or frozen lakes with a snowboard or skis. And then there is kite ground boarding (KGB) where you use a landboard with a kite, the possibilities go on and on...
#9 I have a wakeboard, all I need is a kite
The bindings on a wakeboard are boot-like and are hard to get into, compared to the easy-entry, sandal-like binding of a kiteboard. Basically, when you're in the water with the kite, you're going to want it as easy as possible to put that board on your feet while you're flying the kite.
Try to imagine wakeboarding in a choppy ocean, doesn't sound too good does it? A kiteboard on the other hand, lets you cut right through chop and gives you a nice ride, thus opening up the possibility to ride basically anything.
#10 I found a great deal on a kite off eBay!
Have you ever noticed how every kite listed on there is "great for beginners." Don't believe everything you're told. Just about every eBay kite that I've seen people bring to the beach makes me cringe. Many times, the kite is old (old in kiteboarding can mean anything over 2-3 years old) and unsafe. Remember, kiteboarding is still a new sport, and the equipment today is three hundred times better than it was 4 years ago.
Overall, you get what you pay for! Talk to someone at a kiteboard store for what kiteboarding setup would be the best for you and buy it through them. The right gear makes all the difference!