Are my freelance income and earnings as a part-time student seller of comics and paintings enough to warrant paying the flat freelancer tax, even if I don't meet the income threshold by IRS for regular income tax, and are there any other essential tax-related considerations for someone new to freelancing in Ohio?

If your self-employment income is >$400, you have to file.

What you are referring to as "freelance tax" is actually FICA - your Social Security & Medicare.

FICA is generally paid 1/2 by individual and 1/2 by employer. Currently it is 6.2% for SSA and 1.45% for Medicare or 7.65% FICA - each. That's 15.3% total.

If you are both the employer and employee, i.e. self-employed, you have to pay both halves or the 15.3%.

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You'll want to keep good records of your expenses and income. Look at the categories on the Schedule C form - that's where your income and expenses are reported.

You can use bookkeeping software or set up a spreadsheet or even just use a notebook to track your expenses. It's a good idea to categorize expenses as you go and write notes so you don't have to sort and organize a bunch at tax time. But find a system that works for you.

There are a lot of guides online about recordkeeping - ideally you need to keep your bookkeeping records, receipts (paper or digital), and tax returns for at least three years after you file the returns.

There's a free publication called Schedule C from A to Z that has good examples of the Schedule C categories. Some of the information is a bit out of date but the general categories are still the same. And this wiki has some helpful information:

If you will owe more than $1,000 on your tax return you should start making estimated tax payments. You don't necessarily need to start your first year, but if you will owe more than $1k every year there is an underpayment tax penalty for not making quarterly estimated payments.

If you are a dependent you won't qualify for Earned Income Credit, but if you are independent you are in the income range for that. This credit can cover some of your Self-employment tax.

For tax filing, you should qualify for help from a free tax preparation program. They will require you to have your business expenses somewhat organized, and there are some limitations (no Business Use of Home Expense for example). These programs mostly operate from Feb 1 to April 15, so check the locators in late December / early January for updated listings for next tax season.

Free Tax Return Preparation for Qualifying Taxpayers

GetYourRefund

Since you are selling merchandise, check into your state laws about sales tax. You might have a requirement to collect sales tax if you are making direct sales to people in your state. If so, you'll probably need to register with the state even though your income isn't very high. States generally don't mess around when it comes to sales tax and they can make you pay that tax out of pocket if you don't collect it from your customers.