Do a proper warm up.  Do a light cardiovascular warm-up for a minimum of 15 minutes prior to your lifting.  Your heart rate should be kept in the recovery - foundation ranges.  This can be a light jog or bike to the gym.

Stretch.  Following your warm-up, take at least 5 minutes to stretch out your major muscle groups. (i.e. chest, triceps, lower back, abdomen, calves, quadriceps, hamstrings, etc.)  Hold stretches for 15-20 seconds without bouncing.

Lift enough weight.  Based on your workout prescription, do the required number of sets and repetitions for each exercise.  The last 3 repetitions of each exercise should be accomplished with some difficultly.  This will ensure you are using adequate weight.  Lifting the final repetition with minimal-moderate effort would indicate the weight is too light.

Focus on the prime movers.  Concentrate on major muscle groups and multi-joint movement exercises.  Exercises should be done in the order of larger muscle groups to smaller.  This type of training will involve the most muscle mass and raise metabolism more effectively.

Time efficiency in the gym.  Your workout should not take more than 45 minutes to an hour.  To perform your workout in a more time and energy efficient manner, you can combine unrelated muscle groups in a "super-set". (i.e. bench press, calf raises; leg press, lat pull-down; leg curl, shoulder press)  For example, do set 1 bench press, set 1 calf raise; set 2 bench press, set 2 calf raise.  Then move on to set 1 incline press, set 1 leg press; set 2 incline press, set 2 leg press, and so on until workout is completed.  this also gives the workout an added cardiovascular benefit since there is less rest between sets.

Principles of training.  Follow the guidelines of the overload, specificity, and progression.  In a nutshell, as your system adapts to a training stimulus, you must continue to overload the system to achieve benefits.  You must train the system for gains in strength and endurance specific to the movements of the activity in question.  Finally, you must use a periodical training model that builds a solid foundation, implements strength gains, include sport specificity, and gives adequate time for recovery.

Safety considerations.  Get training on the proper form and technique of exercises from fitness center personnel or a personal trainer.  Remember to use a spotter when possible and safety collars on all free weight exercises.

Don't lift heavy weight initially.  This may be the most common mistake made by endurance athletes who add weight training to their routine.  Remember that your weight-training program follows the rules of progression.  Do not attempt to rush in to the more intense phases of training before anatomical adaptation has occurred.  Take 3 to 4 weeks to gradually build through light-medium the medium-heavy loads.

Use proper form.  Using proper form is crucial to the success of your program.  Improper form during heavy set could result in costly injury to your neck, back, and various joints.  Do not allow hips to lift off the pad during leg pressing movements.  Do not perform overhead presses or lat pull downs behind the neck as it places undue stress on the muscles of the rotator cuff.  Do not arch the lower back when performing bench pressing movements.  All Olympic lifts performed during strength and power phases should be supervised.  Proper form is an absolute must as the ballistic nature of these movements could result in potential injury.

Use smooth, controlled movements.  When performing all exercises, use smooth controlled movements to raise and lower the weight unless otherwise specified.  Do not use the body weight momentum or swinging to assist you in raising the weight.  Do not drop or slam the weights during any phase of the movement.  The Olympic lifts in the power phase of training require quicker acceleration through the initial portion of the lift.

Do not hold your breath.  Throughout your workouts, you will exhale during the concentric phase (raising of the weight) of the lift and inhale during the eccentric phase (lowering of the weight).

Use variety in your workouts.  There are a great variety of ways to train a group of muscles.  Use a variety of exercises and implements to stimulate the muscles.  For example, the bench press can be performed with free weights using a bar and a flat bench, dumbbells, a chest press machine, or a push-up.  The lat pull exercise could be substituted with a wide-grip pull up.  Change the type of exercise or implements you use to stimulate a particular muscle group to keep muscles guessing and keep the workout fresh.