Flight schools are generally made of teflon. This is because they have an amazing knack of rising like a phoenix from the flames of destruction that they have left around them when they go bust. You will find that the astute flight school owner has their a/c owned in a separate company or trust and when you pay over your hard earned it goes into another company. Never the twain do meet. When the creditors come calling the school is liquidated and amazingly enough the CFI sets up from a new portacabin just across the way advertising amazing discounts for "new customers" as part of an opening never to be repeated special.
Avoid handing over deposits and large payments in advance like the plague. Use your credit card in case they go bust even if it means paying a small admin fee.