>have you incorporated?

My state LLC

>Do you pay quarterly taxes?

Absolutely, mail a check with the coupon based on income earned.

>Do you list it as other, unreported income on your returns?

Schedule C and income from business, you pay Self-Employment Tax, SEPs are nice to push off the income to retirement and see a tax benefit if it's supplementary.

I also carry worker's comp and liability insurance, pricey, annoying to setup and deal with but worth it from my perspective.