it's near impossible for a newbie to resistance training to over-train in the first couple of years as the body and mainly the central nervrous system (CNS) is in it's highest most untrained state. remember that it takes the CNS longer to recover from high intensity exercise than it does the muscles. that being the case you have to adapt the frequency of your training to match the level of intensity. if you are using loads at or close to 80% or more or your 1RM then no more than 2 heavy training sessions for each body part every 6-7 days. when training at a lower intensity you can increase the frequency of training. technically you can use loads of 50% of the 1RM and work the same muscles daily with out CNS burnout.