How did conscription work in Nazi Germany?

by IllustriousSea3

Its easy enough to find information on U.S. and U.K. conscription, its deferment and exemptions. But if I were a young man in Nazi Germany, what would my options be for avoiding service? Could it be deferred for education? If I had a particular trade skill would I be specially assigned or deferred? I'm sure it changed as time went on. What sort of medical conditions would disqualify me and how did that change over time?

Thanks!

voyeur324

/u/commiespaceinvader has previously answered Was it possible in 1943-45 Nazi Germany for a fit early 20's man to NOT be in the military? What would one have to do to avoid service?

/u/vonadler has previously written about non-Germans in occupied countries being conscripted to serve in the military, with the caveat that who "counted" as German was sometimes arbitrary.

/u/kieslowskifan has previously written about the competing recruitment needs of the German military and the SS.