I'm in Texas, where we don't have state income tax (but our sales and property taxes are murder). I started with an income (eek) of $12,000. Really. And that was with a rent of $500/mo. Did that for 3 years before jumping to $18K and gradually to $20K. Now that I'm returning to 4th year, I'm going back DOWN to $16K. Sucks.
OH, and you ONLY have to pay quarterly taxes if you will owe more than $1000 in taxes. When I was making $12K, my taxes were somewhere between $500-700, so I just wrote a check in April.