Social Security Disability application?

HI,

I'm assisting my sister through the maze of disability applications. State disability is active and we will soon be applying her for Social Security Disability. Has anyone applied for SSD? Did you require the assistance of an attorney through the process or did you try it on our own. What was your experience?

Any help will be apprecited.

I didn't find the right solution from the Internet.

References:
https://www.lbda.org/phpBB3/viewtopic.php?f=1&t=682
Industrial Valve Video

Thank you.