I run a digital media agency. A year and a half ago, I worked in a call centre. Currently, we're producing a world renowned film festival, have just moved into a studio, and just yesterday recorded a charity music video involving seven quite-prominent Australian artists.
1) By a cheap DSLR. I started with a Nikon D3100 and a 35mm lens ($500)
2) Learn the basics of video editing (you can kinda get the hang of it in an hour. I did.)
3) Find a relatively unknown musician with lots of Facebook friends. Make sure you get one with a reasonably okay home-recording set-up. Offer to film a video for them.
4) How to film: Get them to sit in a pleasant surrounding. Have them perform the song four or five times, with the song playing on a stereo in the background. Move the camera to a different angle after each take.
5) Google how to use the multi-cam function in Final Cut.
6) Load in all your footage, match it with their audio. Slap together an impressive looking video in a day or two.
7) Let them post it on Facebook. If you've done a good enough job, their muso friends will be impressed. Your muso friend will direct them to you.
8) Charge the next two guys $300. Buy a second camera (so you can film from to angles at once, which makes the editing easier).
9) Rinse and repeat. Expand your video horizons (we ended up doing a lot of promotional work for theatre companies). Learn how to use the camera for photography. Acquire better equipment. Respond to clients quickly and politely. If a potential client asks you to do something you haven't done before, do it for free. Learn from that, do it better, and for money, the second time.