I got some tips.
1) One popular choice is just to face your fear, get on and you may turn out to be obsest with big coasters.
2) Make your way up slowly, start of on rides such as a Zierer Junior Coaster, then something like Spinball Whizzer, then up to like a Boomerang, to something like Nemesis Inferno, Colossus and then things like Stealth and Saw, so you end up thinking UK rides are crap, trust me, It happened to me.
3) Don't be intimidated by the noise, the roaring is just normal and other noises like hissing and clicking are only systems which are keeping you safe.
4) If you don't like the stomach feeling, as yu grow older your fat and muscles protect your organs more so they don't move about as much as they do when you're a child, so it doesn't hurt as much.
5) Don't worry about the heights, usually you will find even if you're scared of heights, you are not scared of coasters as you feel safe and secure.
6) If you don't like the waiting, pretend you're queueing for something amazing, and distract yourself by talking or thinking about other things.
7) If you don't like going upside down, keep your head up straight, and don't look at the ground, if you like the feeling, next time feel free to, so you have a more thrilling experience.
8) Scared when you're boarding, maybe it would be a good idea to pick a seat in the middle of the train/car, so you don't feel or see much
These tips got my girlfriend to ride everything, now she wants to go everywhere