Secondary Income
I don't plan on leaving my current career, but I do plan to try my hand at running a very small time tree service. Since you already had your own business, maybe this route would work for you as well. This is my current plan, but may be modified.
I have a few of my own saws from a limbing saw, a pole saw, and a couple 14/16" saws, up to my largest being an MS290. No professional fleet, but they all start and cut. I have a pickup and trailers for hauling brush/limbs (one is a strong but small dump trailer). I plan on getting insurance and probably will start an LLC after more research into the business end of things. When money allows, I'll decide on what to purchase first: 6" chipper, sc252/352 sized grinder, telephone company type 30' bucket truck, mason dump truck, etc.
I am very comfortable cutting and working with trees in my yard and family members' yards, especially after Sandy passed through, but I respect that I am not am not nearly experienced enough to tackle every job. In keeping my full time job, I'll be able to accept the jobs that I know I can safely handle/profit from and say "I'm too busy" for the jobs that I don't feel comfortable working on yet.
Being in the Sandy area as well, it's hard not to jump in knowing the amount of work that is around. However, my current hope is to start up next spring. In the mean time, I am going to really start paying attention to the small around the house and for the family jobs that I do and see how I can do it better, faster, and safer. I also plan on hanging around in the trees in my backyard as I learn how to carefully climb or at least get off of the ground. I'd like to reach $1,000-$2,000 a month the first year and slowly add to my equipment as I can afford it. Worst case, I'm hoping to cover operating costs. Hopefully, I'll see an increase in the jobs as time goes on. I understand many of the difficulties of this profession, but definitely not all.