How do I call for a male waiter? For female waiters, my dad taught me to use the phrase "小姐 ". 

But for male waiters, my dad doesn't know how to properly call them. I discussed the possibility of using "da ge", "小ge", "da di", "小 di", but they sound whimsical compared to the way one calls for a female waiter.

How should one appropriately call for a male waiter?
As far as I know, 小姐 (xiao3jie3) is not very appreciated anymore by waitresses, even in Beijing; they might even be offended because that is how girls who sell their bodies are addressed. That is how Chinese people explained it to me. Waiters, be it male or female, are addressed as 服务员 (fu2wu4yuan2) and it is safe to call them that.