LCD screens don't bother me as far as eye strain goes but I find it most comfortable to read with a "day" theme (black text on a cream background) in brightly lit areas and a "night" theme (cream text on a dark chocolate brown background) in the dark. I switch back and forth a lot. And for some odd reason, I just love
Cool Reader's default paper-like background.
I agree with everyone that says to turn down the brightness settings especially when reading in the dark. Use a reading app that can control brightness settings with a flick on the side of the screen (most of the third party ones do). Also consider using
screen filter to get your brightness settings even lower.
Lastly, get a reading app that lets you play around with different font styles and line spacing. I find that line spacing can make a huge difference in readability.