Only report what you've been paid in checks/moneyorder/digital transaction(paypal)that someone else may report as an expense or that may leave a papertrail.
If you're paid cash w/no receipt, you're good. Even though I report all my income, because I don't want to say I withhold anything on the net.
1099 form works, but that's used to report income you made without paying tax on it basically from doing freelance work. Others here have dropped hints at a better way. I don't know it.