1. No need to pump for the sake of burning fat on the stomach. Getting rid of fat is, first of all, a diet. Cubes are the result, first of all, of a diet for fat burning (or an initially low percentage of adipose tissue). And only in the second - exercises for the press.
2. No need to do several exercises separately for the "lower" and "upper" press. Anatomically, the rectus abdominis muscle does not have a division into the upper and lower muscles, but is ONE muscle. A couple of abs exercises and periodic shifts are enough. Moreover, you do not need to “hammer” the “lower press” if you do not stubbornly see the cubes (see paragraph 1).
3. It is not necessary to overload the press thoroughly before heavy basic exercises. The muscles of the press help to maintain the correct position of the spine, so do not bore them before the movements in which it is important. But to knead, making 1-2 approaches - you can. One of the options for loading the press is to perform a pair of approaches of any exercise on the press at the beginning and end of the workout each time. Then a separate press training is not needed (of course, whether this option is suitable for you or not is an individual thing).
4. The muscles of the press bend the torso. More precisely, with a fixed spine and pelvic girdle, the rectus abdominis muscle lowers the ribs, pulls the rib cage down, bends the spine, and with the fixed rib cage lifts the pelvis. Hence the conclusion - when performing the exercise, you should concentrate precisely on these things: the maximum flexion of the spine in the lower back, which, in fact, sets the trajectory, the movement of the chest down, i.e. to the pelvis (when doing twists), or on raising the pelvis (when doing leg lifts). When performing twisting, one does not have to strive upward, the movement should be directed forward and toward maximum bending of the spine. The more even your spine is when performing this exercise, the less strain is placed on the rectus abdominis muscle. The same applies to leg lifts - your task is not to throw your legs to the nose, but to raise the pelvis towards this very nose, bending the spine in the lumbar region.
5. Do not ease your task jerky. Exercises are performed quite smoothly, the movement down (legs or torso) should also be controlled.
6. If you want muscle growth, follow the same principles as when training other groups, namely, you need to increase the load (burden), you need time to recover, you need an adequate number of repetitions in the approach and exercises for this group. It is not necessary to perform 5 difficult approaches to the press at each training session.
7. If you are a girl, remember that exercises on the lateral abdominal muscles (any in which the body bends to the side and rises from this position) lead to an increase in these muscles (and not to fat burning in the waist) and, accordingly, to some waist broadening. Did you really want this, starting to do the dumbbell bends?