I've been working with new and returning members on this matter for about a month now. Here is the current rundown of what I find works consistently.
(1) Student signs up at
www.firstinspires.org
(2) Student receives e-mail to confirm account
(3) Student logs in at
www.firstinspires.org
(4) Student clicks on "My Dashboard" in upper right
(5) Student chooses the blue box saying "Complete Youth Registration"
(6) Student is sent to STIMS to complete Youth Profile with Parent E-mail
(7) Parent signs up at
www.firstinspires.org using the e-mail address entered by the student. (This is a big problem as students often forget which e-mail they entered for their parent)
(8) Parent chooses the blue box saying "Complete Youth Registration"
(9) Student is already connected with parent's account. Parent completes "Youth Profile" and "School Profile" and applies to FRC ####.
(10) FRC Coach accepts student in their Dashboard.
(11) Parent logs in one more time to complete the Consent and Release form.
(12) Sunshine and applesauce all around!
**NB: For student members 18+, there is no need for parents to log in to complete the profile of the member or school. However, at this time there is a bug where they cannot complete the Consent and Release form. Even if their associated parent logs in, they too cannot complete it. I current have a "help desk" ticket in with FIRST to resolve the issue. May be a Michigan only thing, though.
Hope this helps! :-)