I look for a couple things in a good server and a lot of times it depends on the location or the reason I am in the establishment. If I am there with people and we are getting drinks. I don't want a server who is constantly waiting on us, rather someone who notices when my drink is close to empty to ask if I want another. If you work at a sports bar type establishment you should be that difficult to do. If I am out at a nicer restaurant with family, friends, or my wife I want someone who is attentive but isn't coming around asking if I need anything every 3 minutes. If I wanted you around that much I would invite you to pull up a chair. In that situation I want someone who is knowledgeable but also gives me space.