Practice on low rails that you can't nut and commit your upper body. Once you get one of them, you'll be surprised as to how easy they are. It's also easier if you come into the rail slower for your first few times.
I had this problem, what helped me was getting better at rails, i made sure i could slide loads of them rails both natural and un-natty which helped me gain some confidence, after that i found that i could 270 out and switchup with ease.
Yup this. It has a lot to do with your upper-body as well, use it to generate momentum for switch or 270's out. Start turning your upper body the you want to spin and jump and your lower body will spring with you (not completely but with less effort and awkwardness). 270's just keep rotating your upper body after you've pre-loaded and jumped.
Ride in super slow to a low tube rail. Hop on and land with your front edge set, kind of like pointing your tip up in the air, then just commit. At least that's how I learned front switchups. Backside switch ups feel like I have to spin a little off the lip to start the spin. I used to always ride in to switchup and then hesitate on the rail and end up 270'ing off, you have to just ride in and put your big boy pants on and do it once, after you get it once it's one of the easiest tricks you can do.
scissoring is key, but also dont forget balance/locking onto the rail. Getting fully on centered on the rail will help a whole lot, once you feel locked on and balanced, scissor. Going slow is recommended, more time to do shit. On another note, scissoring can also help you lock on to the rail.
i can hit every rail natural and flat rails unatty, like im super comfortably natuaral and i can sissor allot just fin but it seems like i cant move but i know i can do it, its wierd, and i can spin up to 7 also so its f'd
^ i suppose then the issue is to really push/force your mind to get that spin, as it seems like rails are really no problem for you. I likewise find the mental block far harder to overcome than the physical block.