I was deeply involved with a sport and we had no coaches so we occasionally hired a 16mm film cameraman to come and film us so that we could improve our technique.
This happened to be around the time that Sony released their Rover Portapak half inch black & white kit and we soon learned that the local golf club professional had bought one for coaching purposes. (have you seen one?). A recorder the size of a small suitcase but as heavy as a big one and a camera shaped like a hand gun that weighed a lot.
Anyway we got to hire this thing occasionally to assist us and because I was probably not as gifted as the others in the sport I ended up shooting the coaching material more than the others and found I was reasonably good at it along with a mountain of material that I shot on Super 8.
After finishing with the sport I traveled to England as a part of reorganizing my life and in the late 70's electronic cameras were just being introduced to news coverage - I found that with my years of experience with both electronic and film cameras put me in good steed to point in a new career direction and try camerawork as a profession.
The experience in both areas and especially the shooting of moving objects off allsorts of moving platforms provided me with a good level of skill to start with. Incidentally I subsequently spent a good 12 years freelancing out of London working 20-30 days a month during that time.
As regards recommending how potential cameramen should get into the business? I recommend that they borrow a camera, any camera and spend a good 6 months or so shooting sports matches as if they were being paid to do it. This gives them the experience of following action, working out the best framings for the action, the discipline of continuing until the game is finished usually with a very short break between halves (usually helps to build your stamina and concentration levels also), the skill of sorting out a good stable comfortable shooting position and knowledge about battery life and tape times and getting used to being somewhere to be set up for a particular deadline.
If someone can achieve all those things themselves then they have material to show prospective employers what they can do. To know that they have sufficient passion for the craft to have battled through all sorts of weathers, without giving up. Soon someone will start paying you for the material you're shooting therefore more incentive to keep making it better. I believe that if they try the above then they can make there way in which ever direction appeals.