I had my lateral meniscus trimmed in June, and I've just recently finished a few weeks of physio. However, I went too hard, too soon and have aggravated my knee a bit. It seems to be OK after 2 weeks of rest, but it's certainly an indicator that I was doing too much far too soon.
I'd say to start off slow and focus on increasing muscle mass, particularly in your quads and hamstrings. Wall sits are great for quads, and squats (as mentioned) really help a lot. Just take it easy to start with, and make sure to warm up w/ stretches beforehand.
What surgery did you have, out of curiosity?