Something like this should be adequate for squats:
Weights in lbs (approximate)
65x10
65x8
90x4
115x2
125x1
Then your working sets. That's assuming your working sets are at 75 kgs or approximately 150 lbs.
Read the first page in 0311's "Warming UP Properly" sticky
here to get an idea of how to perform these.
I'm not the king of warming up, so maybe someone can improve on that example, but I think it's pretty good for the fairly light weight you are working at.