I don't use acrylics too much anymore ('cuz they're EVIL!
) but when I did use them, I too had very good luck with alcohol. Matter of fact, that's all I would use for the longest time.
Tamiya's thinner works well with their paints as well as with some others; it has a high alcohol content.
Also, I've tried Smurf Juice (winshield washer solution) and that worked okay too. Like Gordo tho, I dunno what it would do to lighter colors. I'd recommend steering clear of that stuff for, say, yellow! LOL
Fade to Black...