You'll just have to do what the vast bulk of us had to do:
* Don't buy a flashy, expensive car. The cheapest wreck that you can keep running will do. Even better, learn to do the maintenance yourself - you'll save a significant amount. Every dollar (or Euro or Kroner or whatever) that you don't spend on a vehicle is another dollar for flying lessons.
* Don't piss your money away getting drunk with your mates every week. Every dollar (or Euro or Kroner or whatever) that you don't spend on booze is another dollar for flying lessons.
* Don't head off on holidays to foreign climes (or any climes, for that matter). Every dollar (or Euro or Kroner or whatever) that you don't spend on holidays is another dollar for flying lessons.
* Don't go to the movies, or theme parks or concerts or similar entertainments. Or at least, only rarely. Every dollar (or Euro or Kroner or whatever) that you don't spend on entertaining yourself is another dollar for flying lessons.
* Shop conservatively for groceries. Every dollar (or Euro or Kroner or whatever) that you don't spend on luxury items is another dollar for flying lessons.
* Don't be a slave to the fashionistas. Every dollar (or Euro or Kroner or whatever) that you don't spend on the latest & greatest brand name clothing (or electronic item) is another dollar for flying lessons.
* Find cheap accommodation. Parents can be good for this. Every dollar (or Euro or Kroner or whatever) that you don't spend on rent is another dollar for flying lessons.
...is there a theme becoming apparent in the 'don'ts'?
and on a more positive note:
* Do find a job. Any job. Even several, if that's what it takes. Every dollar (or Euro or Kroner or whatever) that you earn can be another dollar for flying lessons. If you don't waste it on the latest iPhone or other widget. You don't need an expensive phone, or TV, or Blu-ray player, or the fastest PC (you will need a PC. If nothing else, to browse PPRuNe for tips and traps to avoid)
* Do careful research about your flying training options. Not all training is done through the large (and expensive!) flying training organisations. There are many, many smaller schools that can give you the *same* licence at a much reduced cost. And in a similar time frame, if you're prepared to apply yourself to your studies. Every dollar (or Euro or Kroner or whatever) that you save at one point of your training is another dollar that can be applied to later stages.
You might be surprised at just how many pilots started their career outside military, airline sponsored or academy-type cadet schemes!
***One last 'Don't!'
Don't pay in advance any more than you're prepared to lose. There are many sad stories of students losing their money when their flying school goes bankrupt. Remember that the schools are competing for *your* business, not the other way around. If a school insists on large sums up front then walk away. There is always another school that is more reasonable.
Always remember that they all offer much the same thing by the end of your training: A Commercial Pilot Licence & Multi engine Instrument Rating & ATPL exam passes (in JAR-la-la land, an MCC course must now be included too). None of them offer an ATPL. They use smarmy marketing terms like 'Frozen ATPL' which many people think is the same or nearly the same as an ATPL. Not so. It's nothing more than (European) industry shorthand for a Commercial Pilot Licence + Multi Instrument Rating + passes in the ATPL exams (& since JAR, + attended an MCC course).
Nothing says that all aspects of your training must be at the same organisation so don't be put off by doing some parts elsewhere eg private at one school, commercial somewhere else, exam theory elsewhere again etc. There is something to be said for being exposed to more than one school's way of doing things. Usually the opportunity to find better pricing but also skill benefits too.