Money-making pre-season HVAC system tune-up tips depends on a number of factors:
Thorough clean and check of residential equipment
Establish what needs to be repaired and when
Present options to customers
Close the sale
It's an old cliche, but it's never truer than on HVAC sales calls: You were given two ears and one mouth. Use them in that proportion. Listen long enough and most people will tell you exactly what they intend to buy and how to close them.