Some good advice!
It is important to vary your strength training routine when the goal is to tone and firm up. This will serve a dual purpose. First, performing a variety of exercises will help the body make changes more rapidly. Muscles can get used to performing the same motion or exercise, which, in turn, will cause them not to work as hard or effectively. Secondly, variety will help prevent boredom and keep you interested and motivated with your workout routine. Try different combinations of exercises and experiment with new machines. This also applies when you do your work out at home. Have Fun!