100 Round Practice (updated 1/25/2020)
To improve your shooting your practice needs to be more than "shoot up these two boxes of ammo".
You need to plan a set of drills to work on specific skills. Here's a sample 100 round practice session.
1) Set up a 6" paper plate at 25 yards. Dry fire 10 times at that target from seated/benchrest position. Many triggers have a two-stage feel, where you can take the slack out and feel a "wall" where resistance to the trigger press increases significantly. This is most common on striker fired guns, and the single action mode of DA/SA style pistols like older SIG and Beretta models. If your trigger has this feel, learn to take up the slack and then slowly press straight to the rear for each shot.
2) Shoot three 5 round groups from seated / benchrest at 25 yards. Use a 6" paper plate as the target. Shoot the best groups you can. Each time the gun recoils, let the trigger fully release (keeping your finger in contact with the trigger but not holding it back or preventing it from resetting), and then take up the slack as soon as the sights are back on target. Measure your group size for each drill and write down those numbers.
3) From two handed standing, dry fire 10 times at a 6" paper plate at 25 yards. Concentrate on taking up the slack and then pressing smoothly straight to the rear, with NO movement of the sights as you press.
4) Shoot two more 5 round groups at 25 yards from two handed standing. Measure the group size and compare them to your benchrest groups. Ideally they should be the same.
5) Set up one 6" paper plate on a target at 7 yards. With an empty gun, aim at the target. Press the trigger until you reach the prep point (right before the shot is going to break) and release the trigger, keeping your finger in contact with the trigger all the way out. Do not let go of the trigger. Work on doing this smoothly in sets of 5. Aim in-out-in-out-in-out-in-out-in-out. Watch the sights the entire time. The goal is zero sight movement as you manipulate the trigger.
6) Load. With the gun aimed at the 6" plate, shoot 5 shots into that plate as smoothly and consistently as you can. As soon as the front sight (or dot) lifts in recoil, fully release the trigger, take up the slack as the sights begin to settle on the target, and start the trigger press once the sight picture is acceptable. Pressing the trigger more slowly will solve many problems. The motion is like putting a contact lens in your eye. Gentle and smooth.
If you do this right it sounds like 5 equally spaced beats of a drum. 1-2-3-4-5. If it sounds spastic 12--3---4-5 then you are not consistent in your grip and trigger control. Goal is all 5 on the plate. If they aren't on the plate, slow down until you can do it properly. Repeat this drill 4 more times.
7) Repeat drill #6 with a 6" target at 3 yards. You should be able to go a little faster but the goal is consistent shot to shot times and precise trigger control. 5 runs of 5 shots.
8) Set up two 6" paper plates about 1 ft apart (left to right) at 5 yards. Start with a dry gun aimed at the left plate. Move your eyes to the right plate. Press the trigger as you move the gun to the right plate.
The gun should stop moving, sights on the center of the right plate just before the gun goes 'click'. Rack the slide, aim at the right plate and repeat the drill going right to left. Do it 10 times each direction dry.
9) Load. With 6, 8 or 10 rounds, start aimed at one plate, shoot it, move your eyes, press the trigger and move the gun, shoot the other plate, swing back to the 1st plate, etc. L-R-L-R-L-R-L-R
Ideally your shot to shot time from plate to plate should be the same as your shot to shot time for the 7 yard 6" plate. Run this drill in 6-10 shot segments to finish off what's left of your 100 rounds.
10) Dry fire 10 times at a 6" target at 25 yards. Watch your first dry shot carefully to see if the sights move. If you are developing a flinch you'll see it on that first dry shot after all that 3 yard blasting.
Those simple drills will teach you accuracy, trigger control, the relationship between speed and target size and sight picture, consistency in grip and trigger control from shot to shot, and the basics of target acquisition.
These don't require any special facilities or fancy targets and can be run w/o a holster or a shooting timer (although you can modify them to use them if you have them).
If you find yourself flinching and throwing shots low left (for a right handed shooter), buy some dummy rounds and put them in your magazine, every other round. Then run 2 shot drills, so your first shot goes bang and your second shot goes click. Paying close attention to what the sights and gun do on that second (dummy round) shot will expose what you are doing on the live fire shot. (Putting the dummy rounds in the magazine randomly is NOT as useful as staging them deliberately in a known sequence. All you learn from random dummy rounds is that you are flinching or pre-ignition pushing. Knowing that the dummy rounds are coming on specific shots allows you to pay closer attention to what happens, and you'll fix your errors faster.)
These drills are good for anyone at any level because you always shoot tighter groups or shoot "clean" on the plates faster.