I am not sure if everybody is now approved for adsense, however in the past Google would need to approve an adsense account for you if you were getting enough hits on your videos.
The way to start is try to see how the popular reviewers do it or your fave reviewers. You need to think it through a little. See how you are going to talk about a particular subject. If its tech reviews most people like it under 5mins. Try to see what your own needs are or something that is unique or something you solved in the past and that might interest people and that is not out there that much. Like if there is no youtube tutorial on something you find online how to do, then this would be a good start. New phones are always good or cameras or even apps. You need to know your shit becuase people will pick it up quickly if you are bull shitting and will cut you up through comments. Talk clear, make sure it is not monotone and put a little of you in it that will seperate you from the other boring guys doing it. Doing the actual video and uploading it to youtube is easy peasy.
I started with a camcorder back in 2010, then worked my way up to a good P&S shoot and then up to a DSLR. I posted many different things like vacation resort videos, photography videos, timelapses,phone videos, and videos related to computers. It took a while for people to recognize me and for the money to start building up, because it all depends on the volume of hits on your video. But now its funny cause I have not uploaded a video in over 1.5 years and am still getting paid.
So in simple terms just start making videos and posting them to youtube and refine yourself as you go and each time improve something else. The hits and comments will motivate you to make more. There is no real answer on the best way to do it because that space is so dynamic...as long as you have fun doing it and are persistent it should work out.
Ok, I can't resist...turning hobbies into money makers...could this hobby be a money maker? ;-)
Seriously, maybe waiter/bus boy, SP driver (but OP doesn't want to use car), or even renting out his place to an agency or something. Making video reviews sounds cool though, and I'm enough of a geek to pull it off I think...how does one get started? I might be interested too cause I could use the extra cash to feed the hobby!