You need to pay taxes.
You may need a municipal license if you are operating a 'business' . Phone your city councillor's office for advice. The staff should be able to tell you.
You certainly, given the product, tell your insurance company. If they are unaware of your business and you have a breakin, you may find they will not cover your losses, even if the losses are domestic (TVs, computers, liquor).
I would recommend contacting Hugh Woods International about third pary insurance. They cover collectors (including coin and stamp) and dealers and are more aware of the parameters of such businesses, than most household insurers.
You need to keep careful records. Even if you are selling as a hobby /garage sale venture, you may find yourself successful beyond your wildest dreams. And if you are, tell us all how.