If you're in a 150/152, look for ice build up on the leading edge of the strut, that's where I notice it
I was told in a 172 to look at the tyres, as white ice on black rubber would be more visible than white ice on white struts. So far I have managed not to fly in clouds below zero (or in rain; snow didn't seem to matter, apart from the difficulty of picking out where the grass runway was).