Good place to start is figure out who the primes are in the areas and scopes of work that you are looking at. Most primes will require you to be an LLC already to even talk rates. Once you get the rate and figure out the volume of work then you can decide if there is a business case for that area. Different primes require different levels of insurance so that can potentially be a big weight in making a good business case.
I'm a prime in many areas so you can hit me up if you want.