Lots of comments here-
As to the OP's question- From my personal experience, I would say that auto mechanics in a large metro suburb is the best field to go with if you want to start working, earning, and learning right NOW with the goal of collecting a decent amount of money quickly. I'd be interested in a
healthy debate with someone who knows of a consistently
quicker way to ERE. Jacob's suggestion of working on boats
is not bad, either, but there tends to be more of a seasonality and cyclic nature to that industry than there is to autos.
As for the suggestion of fire and police, yes, in some
places, you can make that kind of money in 4-5 yrs, but
it can easily take you 4-5 yrs to get the job now
(it took me 3 yrs during the boom times!), also, and
in the fire case you will likely have to go to paramedic
school on your own (essentially an associate's degree)
to get a job offer. Veteran's preference also helps a lot
for police and fire hiring, but again that would take
a few years to get.
Jeremy is correct, municipal budgets are thin, so hiring
freezes and layoffs are a fact of life everywhere.
Layoffs typically go by seniority, too, so now is a
tough time to be getting into public safety work
in many places.
JohnnyH, this would probably need to be addressed in a
seperate thread, but a lot of the career vs. volunteer
firefighter debate depends on where you live and
HS is spot on about the military, too. The benefit package
can not be beat. You could actually save up quite a bit
of money in your first enlistment if you go into the
military with a skill (and thus advanced rank). I think
one could easily "semi-retire" and go into the reserves
(by all means, no offense at all to any reservists intended)
if one saved during their first enlistment and then
applied ERE principles for the rest of their 20.