If your goal is to make progress in the gym, then follow this basic outline for putting together a program:
Start with an all-inclusive warm-up consisting of soft tissue work, stretching, mobility work, and activation exercises. This will take different amounts of time depending on your limitations. Limitations can be anything from being sore and tight from your last session or trying to rehab an injury. In warming up you should gain a better understanding of your body, and reach a level of preparedness that will allow you to get the best out of yourself each training session.
Your first lift should be a major compound lift such as any variation of squatting, deadlifting, or pressing. Depending on your level this can be anything from a modified pushup to a max effort deadlift. No matter the movement, the whole idea of doing this first is to get stronger at that exercise. This is an instance where you are training the movement, not the muscles. The sole purpose for this movement is to hit a record for yourself on the exercise (meaning doing something that you’ve never done before.) Don’t worry about muscle fatigue, or trying to get a pump, just make sure you get stronger each week by lifting more weight, lifting a weight for more reps, or lifting a weight faster.
After you main lift you should pick accessory work that hits your weaknesses. Between your warm up and doing your main lift you should gain a pretty good understanding of where your weaknesses are. Choose exercises that will hit these weaknesses. Doing this will help your progress, and lower your risk of injury.
Once you have completed your warm-up, main lift, and accessory work, then you can get into your specializations. If your goal is weight loss, then do some conditioning and cardio. If you are trying to pack on muscle, do some bodybuilding and really finish the muscles off. If your goal is to be as healthy as possible, then make sure you stretch and do soft tissue work post workout as well. If your goal is all of these things, find out a way to combine them (such as complexes) that will fit your time schedule.
Follow this simple outline consistently, and you will be well on your way to success!