Just save a parentage of every money that you earn just put it on the side, this way you will be able to save money.
It is just like holding on to Bitcoin hold on to your money and not spend it.
But what if someone earn some amount of money and his expenditures are much higher that he will unable to save some money from them, that is what the OP want to ask I think, the better answer is that try to adopt some extra work like part time job and save from there
You will still have to stick to your plan of saving that certain percentage of money. Many people always fail to save money because they always allocate their money to expenses first and what is left is put into savings. That strategy will always fail. But if you set aside the money for saving, put it in a bank or somewhere safe and then work on the money you have left. If what left is not enough for your expenses, you should analyze your expenses and remove those that are not important and stick to basic expenses first. Do that until you find a better job or extra income.