not really advice, but just keep at it.
In regards to boxes/rails. I was a sloppy mess until I started trying to do things unnatural. It made me focus so much more on my balance that as soon as I switched back to natural everything I was trying suddenly felt so much easier and my balance was so much better and I felt so much more relaxed.
Also, don't let people intimidate you. I've gotten used to just giving people behind me a quick heads up that I may fall. They are usually pretty stoked for me when I tell them that I'm trying something new and a lot more patient. I had a group of people I didn't know cheer for me the first time I landed a 3. Made a huge difference rather than the, "fuck, I may fall... I hope no one hits me" mentality.
That being said, I still suck :)