To get along well with customers. If it isn't too busy, (like if there's like one or two customers in line) try to start a short conversation with them. Compliment them. Make them feel at home. I know some customers can be assholes, if they are like that, just be nice enough to avoid getting punishment. And trust me, if you are serving enough customers at once, you will have a huge panic attack (or maybe that's just me). Use the words "sir" and "ma'am". Whenever you're serving customers, getting their food must be your top priority no matter what. Make sure that things are tidied up and clean. The dining room should look clean, and your customers should feel at home.