If you are working toward "bulking up" your muscles, do not do cardio for more than 90 minutes per workout. Too much cardio can cause the body to form "lean muscle" instead of the bulk that you desire. Cardio is very important, but put a limit on it for best results.
In order to effectively build muscle, eating often is required. However, if you have a busy life, it can be difficult to find time to eat. Meal replacements are a great way to fulfill the need to eat if you do not have the time to prepare real meals. They provide a sufficient amount of protein and nutrients, and can also help you avoid eating unhealthy fast food alternatives.
If you are on a program to build muscle, try losing any excess weight you are carrying first. You must consume fewer calories than you burn. Any activity such as mowing the lawn, bike riding or swimming will create a caloric deficit. As you lose weight, you will begin to see your muscles appear. Then it's time to work them!
Spread your workouts out so that you are only lifting weights every other day. Spend one day working out your entire body, and then use the next day to rest. Your muscles will grow while you rest, not while you are working out. Even though it might feel like you are doing nothing on your days off, your body is still working hard.