Helping with classes seems the best. It helps show where you need work. It task loads you with helping and showing others while your gear and diving needs to be a solid assumption. Thus showing you where you need to tune your own stuff up a bit. Not sure how you do that outside of a DM program though.
Some ideas:
- Being a solid diver yourself first. Solid on all the things it is standard to either demo, or do on dives as you guide.
- informal leading/guiding/mentoring a bit less experienced friends.
- Some instructors let prior students repeat classes for free, that may let you 'assist' with out being a DM. You would count against instructor/student ratios unless you are a DM, but most classes should not be near the ratio limit anyway.
Folks really need more info from you beyond 'how do I become a DM'. Where, what are your options, long internship, only one shop in area, to guide, to help teach, from what level of experience, what part of the world, ...
Ahh: Netherlands, Advanced, rescue, night, Nitrox. 50-100 dives., all Padi. Ok. thats could be a decent base. And you have 10+ dive shops there.
Why is a big question:
- To be a better diver? Best to work on skills and experience instead. Maybe cavern, just for the skills. Maybe other agencies. GUE Fundamentals. Maybe intro to tech from a tech oriented agency, again just for the skills.
- To guide?
- To help teach?
For the class, you do have to do things to demonstration quality. But the best way to prepare for that is to get very solid in those skills. Then work on doing them in a smooth fashion that does not confuse the students.