As a 30+ mainly (poor) boat rider here's my tips:
(A tip given to me by a cable operator in London) For standing starts, watch the carrier, when it picks up you're line it will send a wave like an S down the line, wait until the S is half way down to the handle then jump. Up not forward, hold the handle tight to your hip.
Don't try to edge on an obstacle, sounds really obvious but I found myself trying to edge on obstacles with out thinking and it never ends up well. If you get pulled off a rail just go with it.
The guys have already spoke about corners but just to add (this may be bad technique, but it worked for me) as I approach the corner, I let the handle away from me (about a foot), as the carrier takes the corner the line will loose tension, at this stage I pull the handle in tight to keep tension as much as possible. Then when the tension catches you can let is out again to prevent the handle from getting yanked from your hands.
Sitting by the lake looking at kickers and rail you get delusions of grandeur, "yeah, that looks pretty small I'll own that", approaching them at 20+mph on a plank they look very different
Cable is a great opportunity to ride switch and get a lot of time on the water riding switch.