One trick I do with my central heating and air conditioning system to get better air flow is closing off air vents in rooms I am not in at the moment.
For instance if it is the middle of the day and super hot out with my central air conditioning cranking, I will go and close off the air vents in all the bedrooms.
By doing this it makes the air flow in the living room and the whole front end of the house flow much better. Because with the other air vents closed the central heating and air conditioning system is redirecting the air to the air vents that are open. This not only cools my home quicker on those hot summer days, but it also makes the place cool off quicker and in turn saves me some money on the energy use of the central heating and air conditioning system unit. Because the HVAC system does not have to run as much when it cools off quicker. In the colder winter time months of the year I more or less do the same exact thing with closing off the air vents for better air flow. But with that I can speed up the process even more by sometimes running my portable space heater at the same exact time as the central heating and air conditioning system to heat the rooms faster. Of course this saves even more energy than I do in the super hot summer time months of the year. These tricks for better air flow and less central heating and air conditioning system use can be very useful!