I had promised a few pointers regarding using the gym experience to become fitter or maintain fitness. Do not use my advice without consulting a doctor first. Everybody who does anything should do so only on advice of a doctor. I wonder if anyone has ever done that (consulted their doctor). I imagine the doctors must be pretty busy with this sort of thing. Anyway, what I have learned from Lenora, books, and experience:
You should do exercises in a certain order, and this order can be conceptualized at different scales of time.
The very first muscles you should work on, as in "I've never exercised at the gym before, what do I do?" (Not as in "I'm at the gym for the billionth time, what do I do first?") are your core, and particular, rotator cuffs, as well as lower back and abs.
Rotator cuffs are very easily injured. They are muscles and tendons that stabilize your shoulder while other bigger muscles are doing their thing. People often injure their rotator cuffs and these injuries can be quite severe and stop you from doing any other upper body exercise for a long time. Don't mess up your rotator cuffs. The exercises you use to strengthen these muscles can be found in a book on exercise and involve very small dumbells. Whatever you do, don't work them hard. Work them easy, work them every day (almost) for several days (unless they hurt), and always, always do this before proceeding to other, more intense, upper body work if you've not exercised for a long time. After exercising the rotator cuffs, don't do anything else with your arms right away. In other words, let your rotator cuffs get in shape before you demand that they do their rather difficult jobs while you do other upper body exercises.
There are two exercises that I learned, but there may be others, for rotator cuffs (again, find a reliable reference or ask a trainer for advice on this). In one you put your arms out to the sides and drop your forearms like you were a rag doll, and then lift the forearm to parallel to the ground while your elbow is still bent, with a very light dumbell. If you do this and it looks rather silly, then you are probably doing it right. Over time, make the dumbell heavier. Start with two pounds, work your way to five. No more than five, ever, unless you are a robust person.
The other exercise involves having your arms to your side but your forearm out straight, like you were holding ski poles or about to clap your hands. Hold light dumbells, and move your forearms out away from your body and back towards each other, slowly. This also looks silly when done correctly. Again, use light weights, don't overdo it, slowly build up the weight over several days, and don't do other major arm exercises until you've done this for a few days to a week.
In the meantime, all the other exercises you do initially should be done on machines if possible until you are somewhat trained up, then you should add dumbells and eventually swith to a high proportion of free weights. You should use light weight settings at first, and don't stress your muscles at all, until you've done this for a few days for each excercise and built up a bit of stamina and learned to make the motions properly. Improper form means injury. Proper form means lower risk of injury and better results.
In most cases you are trying to isolate a muscle (or two muscles) and work only that muscle. Keep reminding yourself of this as you do the exercises. If you find yourself using lots of different muscles to carry out a simple exercise, then you are doing it wrong .
Look at the picture on the machine, get a book on exercise, whatever, to learn the techniques. Reps should be slow; Usually your push (where you are pushing against the resistance) is faster than your return, which is slower. Some muscles are best exercised faster, some slower, and for some, the speed is actually a variable you will want to change up. But overall, when you are first starting out, most people should go slower than their natural instinct will tell them in actually doing the exercise.
Slow is important in the beginning because you must perfect your form to avoid injury. I may have said that already. Oh, and by the way, it is important to have good form to avoid injury.
This post is very important for all people who do exercise to read and keep in mind at all times. I couldn't agree more that proper and correct warm up exercise before starting with exercises that involve higher intensity and heavy weights. Most people end up doing more harm to their bodies than good because are uneducated about exercise. Most people just want to lose weight and get into shape in the least amount of time possible and, in the end, cause a set back on their road to fitness and a healthy lifestyle. Therefore it is crucial to keep in mind that looking after your body by warming up properly, to be able to keep going on your fitness journey and reach your desired goals.