I just joined a gym last week. So far I really like it - a wonderful stress reliever. Problem is, I don't know what on earth I'm doing! I go for about one hour every other day. Is there a "right way" and a "wrong way" to do the gym? Should I focus on cardio one day and strength training the next? Mix it up 30-min/30 min? I'm looking to maintain my weight and build muscle, by the way. I don't need to lose weight.