Jason Heath, a double bassist in the Chicago area, has posted a wonderful essay on life as a freelance musician. It should be required reading of anyone majoring in music performance. I heartily second all of what he says--it's a jungle out there.
I would also add that if you move to a big city like Chicago, not only do you have to compete with the Professional Orchestra musicians and the college faculty members (who may or may not be members of Professional Orchestra), but you also have to compete with the students of these faculty members, who often have a leg up because of who they know.
I would also add that if you move to a big city like Chicago, not only do you have to compete with the Professional Orchestra musicians and the college faculty members (who may or may not be members of Professional Orchestra), but you also have to compete with the students of these faculty members, who often have a leg up because of who they know.