How much should I send for a tax payment in order to receive the maximum in Earned Income Credit and Child Tax Credit?

Hello, I am self employed with very low annual earnings ($5,000) Last year, I made a $300 payment to IRS for taxes so I would qualify for the earned income credit and child tax credit. I got a $2,072 refund. I am wondering if I should send a larger payment and if so how much, in order to get the maximum credit and refund for the EIC and CTC?

 

Thank you for your time.