Aviation

That's a very logical and important question. One must ensure the following points before choosing any flying school.
1. The DGCA approvals of the flying school, their validity and no incident/accident record.
2. Condition and ownership status of the aircrafts - sometimes Aircrafts are leased and if the lease finishes in the duration of your CPL Training you may be hung for a very long duration. New aircrafts with improved technology are always good because they keep you closer to the requirements of airlines.
3. Status of the airfield - Controlled or Uncontrolled airfield must be checked. Because a controlled airfield will allow you better exposure to ATC functioning and flight planning. It will also save you from any fraud flying.
4. Availability of Navigational services - If the airport has got adequate facility of navigational facilities like ILS, VOR, DME, PAPI & VASI. You shall become a better pilot than those who will fly at airfields where all this does not exist. And you will also GET your CPL issue checks done on your home field instead of looking for any other airport.
5. Geographical location and terrain - It should also be kept in mind. Because geographical conditions and weather impacts the training flights most. Good geographical location like Rivers, Railways tracks etc. Allows better visual flying experience. Weather should also be considered because sometimes bad weather or rainy conditions adversely affect training flights. Training Aircrafts are small and less powered as compared to any jet aircraft hence cannot be flown in heavy gust or rains.
6. Availability of AME - It is very important to keep the aircraft in good condition all the times for training. And good AMEs conduct a daily inspection before the first sortie, this ensures the safety of pilot and the aircraft both.
7. Availability of DGCA Approved CFI and instructors - Now, this is the most important point to see. Because good and experienced instructors will always guide you better than others. CFI will help you conduct your checks smoothly and timely.
8. Good Ground Instructors - Ground Instructors help you in gaining the basic and most important theory which each pilot must be aware. It will also help you in clearing your CPL exams conducted by DGCA. I think I've listed the major things that you should keep in mind before you join a flying school.