Disability?

Given how bad my symptoms have gotten recently, I am looking at applying for disability. I would like to know what everyone's experience is with it. What was it like for you, was there anything you learned to make the process easier? Is there anything they've put in restrictions making it impossible? Are there "secrets" (for example- some legal things you need to say the right words in order to qualify, even though they should qualify regardless in regards to insurance coverage) you've learned? What are the guidelines on the level of disability (or is it all or nothing and levels/percentage is reserved for vets- as I've only been aware of details of veteran disability in recent years)? How involved should the medical info be- did you have just how unable you were to deal with daily activities in your medical files, etc? Any info is appreciated. Thank you!