What were the ways German males could have evaded consription/draft during the WW2?

There were not many ways, and virtually 0 easy / comfortable ways to avoid being conscripted in to the Wehrmacht (Military), especially as the war dragged on in to its final years.

So lets say you were a young healthy German man of military age (say 21) named Hans, and war was looming over the horizon, how could you get out of being called up to join the Heer (Army)?

Firstly, you had probably done a stint with the Hitler Youth, as that was almost (but not entirely) compulsory when you were in high school (but could also have been too old for it, given what year we are talking about). The Hitler Youth then sent its members to work for a stint with the Reichsarbeitsdienst (Reich Labor Service "RAD") where you would spend several months digging ditches, working on roads, or helping German families plant or harvest crops . Usually this happened before going away to college, joining a trade, and or going off in to the Wehrmacht or SS.

You do not want to go in to the military, so doubtfully you wanted to join the SS. Clearly you were not inspired by your time with the HJ and the RAD, so what do you do?

At this stage the easiest options are one of two. You either go to college, especially if you are very proficient at something (hell, even early on, you could still get a draft waver if you were going to college even to study music at a conservation, but that's stretching it a bit). You would have had to have very high marks in high school to be able to place in to college. You also would have had to have gone to a good high school that you placed in to when you were younger. This is not modern day western world where you can kind of pick and choose what you do, and just float around in college without picking a subject to study and a career to work towards. This is late 1930s Nazi Germany. So you should pick a valuable and essential field to study in college, essentially anything STEM related.

Alright, so you decide to study mechanical engineering. You figure that you really want to get of going in to the military, you have always had a knack for fixing things, making them work, and of course math. You figure that this degree will help you work for an automobile manufacturer, or maybe the railways. Yes, the railways, that is one way to really get out of serving abroad. You can work making trains run more efficiently, and maybe design them. That is a purely exempt from military service related industry, especially considering how much the military heavily relies on rail transportation. Perfect! Or so you think.

You go college, and then after a year, the war is in full swing, and they need you to quit your studies and go work as an apprentice at a rail yard outside of say, Hamburg, or any other major city. You go to your job, and do your job well. You either stay on the job and risk being strafed and bombed later in the war by allied bombers, OR you end up being essential, sent to work as a mechanic in the Army, or serve guarding trains. You are attacked frequently by Allied fighter planes, and or by resistance organizations. If you are a train guard or physically working on the trains, once you have been drafted in to the military. OR, you are a mechanic for a Panzer unit. You do not want to be in the Army, but you are stationed somewhat behind the lines, and you are the one fixing the tanks, not actually fighting in them. However, as the war, specifically the Eastern Front drags on, and your unit is pushed closer and closer in to your home land, and tanks are being destroyed faster than they can be replaced, you are now in a relatively useless role, and along with other mechanics, cooks, clerks, tankless tankers, the lightly wounded etc... you are now in a scratch infantry unit on the Russian Front. Fantastic! Sarcasm. This is exactly what you wanted to avoid. So what are the other options?

The other main option, at least at first, to get out of military service was to go directly in to an important war industry. Ok, you decide to go work in a factory, or a coal mine. You are safe for a couple of years, until POWs, foreign laborers, and concentration slave laborers take over your job, and you are sent to join the military.

So the two easy ways out of joining the military will eventually lead you to be in the military, or at least be under attack during the later years of the war. And since you are HEALTHY, you cannot get out of the military for any form of physical ailments (and you certainly would not want to have any major physical abnormality / defect, lest you be sent to a Concentration Camp). So you are really stuck.

The only option would be for you to "dive". "Dive" / "Diving" were the slang terms used in Nazi Germany for individuals who went underground (for whatever reason). You are an ethnic German Christian, with no Jewish heritage, your family is relatively Conservative, albeit not Nazis, so outwardly you are fine from any direct persecution. You are straight, you are not Jewish, you are middle class, you are not affiliated with opposing political parties / ideals etc... you are like most other young German men of that time. Yet, you are secretly subversive and an anti-social (things you would have been deemed and punished for, for draft dodging early on, if caught. If caught later, you would have been deemed this, and an enemy of the Reich, and a deserter. Things you do not want to be labelled in Nazi Germany). So you decide to go underground.

However, going underground has a lot of problems, especially in Nazi Germany. For one, you have the obvious. If you cannot produce official papers when stopped by the police, or heaven forbid the Gestapo, they are going to wonder why a normal healthy looking young man is not in the military or in some war industry, so you will be carted off to the nearest jail, and interrogated. You will be investigated and vetted. The Nazis for all of their horrible faults, were amazing record keepers. They are going to see that Hans Schmidt has been living off the grid for a while now. You will be tried for the earlier mentioned things, and sent to prison, or a Concentration Camp. Eventually you will probably either work in inhumane conditions in a war industry, or may be pardoned, but join some military unit, or worse, a unit like the Dirlewanger Brigade / 36th Waffen SS Brigade (which was made up largely of German prisoners, poachers, and other undesirables, led by a former Pedophile Rapist. This unit was horrible to occupied peoples). If caught later in the war, you will be tried, and shot and or hung, with your body hanging from a tree or lamp post with a board draped over you saying things like "deserter" and "coward" etc...

So you will have to go underground for a long time. You will have to stay underground for a long time. You cannot walk around openly, at all. Unless you know an amazing forger, or know someone with connections to the local police / SS - but they may turn you in at some point, especially if they are feeling pressure themselves for whatever reason. You will need people to hide you and help you during your time in hiding. You will need them to get you food, and other items to live off of. They may have to move you to other locations with other people for fear of being discovered, and they themselves ending up in a camp or dead. You are putting others at risk. And many may be resentful of that, especially since you are otherwise perfectly fine in Nazi Germany (you are not a Jew or a known Communist Official). Why should their sons, husbands, brothers, fathers etc... have to go off and fight, even if they did not want to, while you are living in someone's cellar? As the war drags on this resentment will grow, especially with bombings and rationing taking full effect. You may find former hosts to not be as kind. And since you've been missing for a while, you may end up dead and dropped in bombed out house somewhere. Or your hosts may take a liking to you, and you may survive the whole war. Good luck telling that to occupying Allied powers who will suspect you of being some kind of SS official on the run, since you have no real paperwork or history you can back up, except you did not want to fight. You need a true reason to help you back this up.

The only other option would be to immigrate, whether legally (get a visa and all of that), or by crossing in to one of the neighboring countries, but then, how well would that work out for you if you were not in Switzerland or Sweden? Unless you migrated outside of Europe (minus the UK or neutral countries) you would be swept up at some point with the advancing armies, and either join local resistance organizations (so fighting, but now against your own former countrymen), or go in to hiding. Or fully change your identity, and hope no German official notices.

I hope this little response helps show you how hard that would have been.