I personally think being a barback is waste of time if your goal is to be a
bartender. I have seen barbacks spend years waiting for promotions, only to
get passed over. If I were you, I would look into a slower bar to get some
experience. Bars that are slow are always looking for people because the more
experienced bartenders are usually working in the busier places. While you
may not make 500 a night, you'll be able to get your foot in the door.
"Chain" restaurants offer great training but usually require you to be a
server first, before getting promoted to bartender. The problem with that is
if that manager doesn't like you, you probably will never get promoted. Once
you get a bartending job (no matter where it is) you have "experience". That
"experience" will lead you to get better bartending jobs. Getting your foot
in the door is the most important/hardest part. After that, its easy. Best
of luck.
Pete