As someone who spent their youth engaged in the parachute arts I don't think a practice jump is going to help. Tandem ground school and jump experience is useless, accelerated freefall is better but 99% of it is irrelevant. They are training people to be skydivers, not bailout survivors. Find someone that once jumped lots and now flies sailplanes and have them teach you.. Or a rigger, they have an idea of what our community needs to know. Which at its simplest is:
Look for the handle, reach for the handle, pull the handle. And as Dave said in the video consider a static line, if you do use a static line have the same mindset - Look, Reach, Pull. Have a goal of being faster than the static line. You won't be, but you'll survive if you forgot to clip it on.