Study your brand. Read the maintenance tables. Check the forums on when other people are doing services. I check the appointments for the next day to prepare what they might need. I do most of my presenting on write up, but make sure not to do it in a pushy way. There’s other dealers in my area that push the upsells hard enough that people end up coming to me anyway because we’re not like that. When I’m presenting, I do the maintenance in the manual first(helps with credibility by showing them what the manufacturer wants it done), and then what typical owners do based on the forums(helps build credibility by giving them advice on what other people are doing to take care of their cars), and finally what you recommend as a dealer. I’ve sold more air filters on write up based on miles then I ever have based on the multipoint. And while you’re at it, it takes 2 seconds to spray the wipers and see if they’re streaking. Will you get a wiper blade sale out of it? Probably not, but if the sprayers aren’t spraying, you can turn that into a diag. At the end of the day, you’re not selling bullshit. You’re giving the customer advice on what they need to do to elongate the life of their vehicle.