Spyder made some good suggestions on ikitesurf for new kiteboarders that have completed lessons but are on the brink of waterstarting.
my suggestion would be to practice your lesson material by yourself
(and maybe get a partner to help with launching/landing).
continue to watch the videos, and work on that kite control. most of your
trouble will be kite issues, the board edging is a bit tricky but nothing too
here's the top common mistakes beginners make:
1). their back is *not* square with the wind direction (so they dive the kite
off to the side, resulting in low power). make sure your back is centered
on the wind direction.
2). not diving the kite hard enough to get up. you need some power to
get your butt out of the water. obviously too much will send you over the
rail, but the initial yank has to be good enough, so dive that kite! as you
feel yourself coming up out of the water, turn the kite back up, so the
power stops momentarily.
3). board is pointing too far upwind, so you round up when you try to dive
the kite. make sure the board is across the wind, or even pointed slightly
downwind. this will help you get up more consistently.
4). sheeting out the bar too far, kite flies all over the window. beginners
tend to let the bar out too far, resulting in the kite losing too much power,
overflying, and lack of control. pull that bar in! and pull to get a good dive,
then when you get up, keep that bar in closer, so you can steer the kite
5). steering the bar like a car. remember turning the bar does absolutely
nothing with the kite steering, you need to think push and pull. that is all.
keep the bar in a comfortable, level position with your body. many
beginners tend to tilt/rotate the bar and lose orientation with the kite and
the steering. if you maintain a fairly fixed position with your arms (of
course you need to move them in/out for steering and power control), but
you dont need to tilt or rotate the bar and have an awkward position.
6). once on the board, the weight is not distributed, kiter falls off. once
you get up, you need to have a straight back, firm stomach, and bent
knees. you need to position your weight so you dont fall off, to edge the
board, and to favor your back foot. all this will help you stay on the
board. maintain course with your front foot, and keep good pressure on
the back foot.
7).zooming downwind at breakneck speed. this happens a lot in the
beginning, because the kiter has lost the edge control and the kite is still
powering them downwind. think "slow", when starting to get up on the
board, make sure the board is situated across the wind, get up and
maintain the back foot pressure. if you start going fast, push hard on the
back foot, and try to maintain a good edge. you can also bring the kite to
12 oclock, and surf under the kite. also a key tip, is to make sure the bar
is in front of you, NOT ahead of you. if the bar is ahead, then you will be
pulled downwind. try even moving the bar slightly to the rear of the board,
this will help you go upwind.
I would add to this list, going out underpowered with either too small a kite for the wind, too little wind or perhaps too short a board for the wind and the board. The most common problem that I see is failure to attack the kite down or up aggressively enough and failure to point the board about 120 degrees off the wind. A great time to initially develop a feel for the powerstroke is during body dragging with the board onshore.