If restaurants tested, they would not be staffed.. lol.
I've put in a good decade in food service and far prefer the other side of the line- the greasy side, where the customers don't sass ya.
Get a very good reference at your first waitstaff job so you are in a good position to get hired at a restaurant locally known for staff making bank. Diners are chill, but the tips can be funky- you get a guy sitting there for a couple hours over coffee and that's going to be a few bits of change on the table. You want your guests to spend as much money per hour of your time as humanly possible... if you get a table's check up to $100 by suggesting appetizers, dessert, that nice bottle of Bordeaux... more money in your pocket when they leave you that $15-$20 tip later.
Also practice sounding sincere even when you're not so that you can fool assholes that you want to kick in the teeth into thinking you are 'nice'.
(Sorry... been there, done that, grown a bit cynical)
Good luck!!