A lot of the above cant help you if you have a fuel leak in flight, gauges are the only real means of detection until it all goes quiet. Some have mentioned that the gauges on some aircraft are very inaccurate but what they really mean is that they tolerate flying unservicable aircraft.
I agree, but beggars can't be choosers.
A renter can't walk into a school and demand they rip out the crappy 30 year old gauges and replace them with new ones.
Duff fuel gauges are an integral part of general aviation - tolerated along with all the other crap we put up with.
The only "escape" is to rent from one of the very few schools that have modern fleets, or scrape up enough money to buy something decent like a TB20GT with a 28V system whose capacitive fuel gauges are accurate to a few percent. But the TB20 will probably have a flow totaliser anyway.
Of all the planes I have ever rented, not one had gauges usable to the extent of being worth reading for any fuel management purpose. This includes PA38, various PA28s, C150, C152. I have never trained in any plane whose fuel gauges were useful.
That's why one has to either play very conservatively (starting from a physical check) or establish the fuel flow experimentally and then basically work on timing the flight.
Being a professional pilot dosnt make for better fuel planning(as suggested) all the low fuel emergencies I can remember involve professional pilots.
That's because professional pilots think they know how close to the line they can go
But ultimately you are only as accurate as your equipment, and an awful lot of "professional" flying, at the piston end of things, is done in old wreckage, which is just the same as the wreckage used for training, only bigger and with more engines. The pilots of the ancient clapped out Trislanders for example have no better idea how much fuel they really have than a GA renter.