Pro tips:

Many jurisdictions don't require you to have a business license if your revenue is under a certain threshold and the work you do is unregulated. Basically, you can just decide you own a business at any time without filling out any paperwork.

Housecleaning, auto mechanic, and IT consulting businesses aren't regulated and can be used to justify 90% of common purchases. A YouTube channel is a business and can be used to write off anything you make a video about.

Any major purchases you made throughout the year can be declared as an asset of your business. If you say you only use it for business 50% of the time, it's practically impossible for anyone to disprove.

Also, 50% of the money you spend on those major purchases can be declared as a business loss, which further reduces your tax obligation.

So, let's say you bought a PC and a 3D printer this year. You can decalre both as assets belonging 50% to your business, declare half the cost as a business expense, and declare no income from the business. You can also declare half of your gas purchases as being for your business. You'll get a credit for the asset, and a credit for the "business loss."

Basically, you can create a company that has your home address as its HQ, say it didn't earn any money, but you invested in it. Then, declare ordinary purchases as assets and investments into the company by saying you use them for business 50% of the time.

There's no requirement to have a business license before telling the IRS you have a business. There's no requirement to run a business "well" and there's no penalty for running a business badly. Receipts aren't required to declare assets or losses, but you may need them if you're audited. You're unlikely to be audited due to the 50% declaration. If you are audited and you have receipts, you're covered.

Disclaimer: I'm not a tax professional and this isn't advice.