Every game needs practice. Without proper practice you can never impress others and even yourself with your performance. Same is the case with golf, as it's a difficult game and requires great practice from all golfers. Though, there are various golf teachers who provide exceptional hands on instructions, but unfortunately fail to provide student golfers with a proper practice plan or continuing self critique.
There are also some teachers who use to teach only for money, and try to spend least time on students so that they could get new students in. So all this results in the golfers making more mistakes and feel less confident while playing. Make sure that only practice doesn't make you perfect, but perfect practice makes you perfect.
It is certain that for a normal golfer or non professional, it is very hard to find enough time for practice. Even when the golfer finds the time to practice, the method he uses is inconsistent and blemished, so it results in the process becoming insufficient and longer. Keep in mind it doesn't matter how long you practice, what matters is how you practice. You can consider the following points for a good practice exercise.
First identify where you are weak and what you need to practice first. Don't try to correct everything at once as you won't be able to, and it would prove to be a time wasting activity only. So, focus to improve your most significant weakness first and then move on to others.
Try to find out a suitable remedy to your specific problem, which you have identified. For this purpose you can refer to the professional teachers or your coach if you have one. Also try to find out more than one solution or remedies to fight your specific problem, as attacking a problem from different angles and with different tactics can be very helpful.
You should use a mirror, friend or any other helpful tool for feedback. For example, if you are working to improve your spine angle, you can set a masking tape on the mirror where you desire your spine angle should be, and then look at the mirror to see if you have got what you were expecting.
If you want to improve your driving range then hit the golf balls slowly. Though, the establishment would require you to beat the balls quickly so that others can get in and play, but you should take your time for every attempt and maintain records of your results. One simple way to take time is to place the balls behind you so that you couldn't hit them so early.
Most importantly maintain notes of your improvements and practice sessions, and evaluate them on a daily basis. Keep in mind that you are wasting your time if you can't measure your performance. You will not get favorable results in the beginning for sure as this is common and normal. But stick to your program and compute your results in the form of number of balls hit properly, drills completed, and also try to evaluate your confidence level in every session.