As you move forward, it is important to formalize your business and make sure you have legal aspects to protect yourself in place.
Business Startup Checklist - use this to help you make sure you take all the necessary legal, state, local, and basic steps to launch a business
The default city is Lowell, you'll have to look up for your town/city
You will have an option to formalize by establishing a business structure. Learn more about the variety of business structures HERE from the Small Business Administration.
You can follow step by step what is essential to establish by reviewing this page from the Mass.gov website HERE.
Choose formal structure
Understand tax obligations and register to pay taxes (learn more HERE)
Get a business certificate in the city/town where you are established. Find out more by contacting your city/town or HERE.
Apply for EIN number HERE
Get insurance for your business
IMPORTANT NOTES
It is highly advised that you meet with a tax accountant to determine which formation is best for you in your situation. Additionally, you may want to meet with a lawyer to discuss any potential liabilities your business may have that you will want to protect yourself from. For example, if you are a food business, this is a high-risk busines that should have liability protections in place.
Do not pay for an EIN number. There are a lot of websites that say they will do it for you for a small fee, it does not cost money and you can do it yourself with the IRS, see link above.
Same goes for filing your business with the state. You can pay a lawyer to do, or you can do it yourself.
Contact several insurance companies to get a good sense of coverage and costs for your industry.
If you are partnering with anyone, be sure to work out a partnership agreement first before moving forward so specifics about who does what and how much each will make in profit or worked out before any issues can occur.