I`m going to go out on a limb and suggest the following. For those of you who don`t agree, please don`t bash me too badddd... 
I generally suggest people jump right in and work out the details as they go. Incorporating? Business Licenses? Insurances? That all can be worked out as you go. I say this because most people get caught up in getting everything "Just Right" before they get started and before you notice, 2 years have passed by.
And when they finally get into, many find they have NO market (or the market isn`t responding to their offer). Sometimes, people fall in love with their products and will waste time, money and resources trying to bring their product/service to life, when indeed there is no life.
But if they had tested their ideas, products or services before spending thousand or wasting time, they would have found the idea was no good to begin with.
Should you get insurance? Should you incorporate? Should you get a license?
Of course you should...but most people can put that on hold initially in an effort to just get things going and once you start getting some money, those would be the first things I`d start doing right away (sooner than later).
Now, if you have products/services that are "high-risk" or theres the probable chance that someone or yourself included, could get hurt/injured, then yes, you probably need to employ those things before you even consider getting started.
But if you`re selling socks...then those things could wait until you start generating revenue.
I`d personally would probably get a business license since they`re so cheap and many of the vendors you deal with will probably require a Sales Tax ID # so you can purchase stuff at wholesale rates, but other than that...
I`d encourage people to simply get started...
With that said, you need to know that I`m not an attorney, and should you need advise, I would encourage you to speak with an attorney.
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