I never used to be a gym-goer. Last year we joined the Y and went three times a week without fail for 11 months. At that time, I stepped in a Lego and ended up with a foot infection and couldn't work out for eight weeks. Then we got lazy for another 4 weeks. But we are finally back at it.
Any exercises to avoid? I usually make the rounds on the Cybex circuit. Hubby and I walk two miles together first and depending on time constraints, end with another 15 minutes of cardio on the elliptical.
Any machines that I shouldn't do now? I read one article that said nothing with an upward motion like some of the chest press machines. But I didn't understand why. And I avoided some of the less controlled exercises--not exactly free weights but the machines you stand up to use and can adjust for biceps and triceps? I forgot what that's called. (This multi station thing: http://www.cybexintl.com/products/jungleGym.aspx)