How many days per week should I work out?
How much is too much?
Goals, experience, and available time will dictate how much time you should be spending working out.
If you are a beginner, it is best to start out with 3 days a week. You will need ample recovery time as your muscles adjust to the challenges being placed upon them.
Once you progress, you can choose to continue completing 3 days a week of strength training and supplementing the days in between with cardiovascular exercise such as jogging or biking. This type of layout would be ideal for a general fitness program.
If you have a more advanced goal in mind such as bodybuilding or sports-training, then your variables would change. As a bodybuilder in training, you will be spending 5 to 6 days in the gym, focusing on pure strength training with minimal cardio. If you are training for a sport then you would be splitting 5 to 6 days between the gym, the track, and sporting practice.
Regardless of your goals, be sure to allow yourself 1 to 2 rest days in between your workouts to avoid over-training.