i can do most doubles of the boards, not on skis yet though unfrotunately
misty/rodeo - throw it down like your gonna do a misty of something really short, grab your shins and bring your knees into your body, and once you come up from the first flip, look over your shoulder and roll into the second
rodeo 7/misty - similar to the one above, but set it like a rodeo obviously, with less flip rotation, and set the spin harder, and when you come around after the first flip, roll down towards the water for the second one.
kang/double flat- set it almost like a you would a lincol, but throw it hard, and make SURE you look directly up at the celing in the first flip, and for this one its easeir to wrap under the knees, almost like your doing a japan on skis.
double gainer - make sure you get off the board before you sling it. thats my only tip for that one.
aerial backflip- pretty easy doubleflip, but really easy to overrotate. it always seems like you're not gonna make the backflip around, and you end up tucking hard, then overrotating. thats me anyways. set and aerial (laid out) super hard though, and once you come around bring your knees to your chest and look straight back over your head
double cork - this ones wierd, i dont ave it perfect yet. but set it down like your doing a cork 5, ive found that leading mute helps me do this one, and just spin really really fast. after the first cork it feels like you're completely fucked, but just commit, keep spinning and you'll come out of it.
thats al i have
best of luck man.