For example, if you live near a metro US city, you might want $50/hr, which is pretty low. However, you'll be up against developers around the world where even the most experienced may charge only $10-20/hr. Not trying to burst your bubble but why would they want you, who potentially costs more than double? If you can't answer that question, then they can't either.
Judging by the attitudes and responses I see online from both sides of the North Atlantic, and from both ends of the Pacific, my first response would be ... "native English speaker/writer, and contactable by non-international telephone calls within the same / very similar time zone".
My second response, based entirely upon a very visible/vocal online trend this last couple of years (will only work for US citizens though) is to play the "(I was) Made in America" gambit - I am seeing incredible amounts of "don't buy from foreigners" type sentiment online nowadays coming from US business people and private citizens - it's really scary, and very much parallel to China in the 1950s before they closed the borders.
Still, if it works for you .... ;-)