I've recently been pursuing the possibility of voting in the upcoming US presidential election, since I am a US citizen. The trickiness is that I have never lived in the US but am a citizen by virtue of my parent who was born there.
The UOCAVA protects absentee voting rights of some citizens overseas, including those who have never lived there.
Here's where I've been looking; perhaps it will help you if you're also considering voting absentee.