Just write down what you spend your money on. At the end of the month, review. You might want to classify things, graph total expenditure and other fiddling around with the numbers. But that’s all you’ve got to do: just monitor things. If it turns you on, the monitoring etc can be done via a spreadsheet or personal finance application, but a sheet of paper marked out with every day in the month will do just fine.
When you become aware of what you’re spending your money on, and look at it as a proportion of your monthly spending, the awareness alone may be enough to change your behaviour to be more fiscally responsible.