Nive to see someone concerned about this. The $10 pre passenger per day covers your dining room waiter and asst waiter (aka bus boy) and your cabin steward. Drinks ordered from the bar have the tip added on automatically.
Room service is not really covered. We take a bunch of singles with us, tipping a dollar for some coffee, up to whatever seems to match the amount they bring. I don't try to get fancy about calculating this, but if they are carrying a huge tray, I tip more.
Otherwise, it depends entirely on service received. I do not automatically tip the maitre d' or anyone else in spite of the cruise line always trying to get us to do that. Unless, of course, they do something extra for us. And, I rarely carry cash around on board anyway. But, if someone gives me service above and beyond, I tip at the end.
As an example, we were on a 16 day HAL cruise. I smoke, hubby had quit, so I would go up to this one bar when I wanted a cigarette. The first two times, I aske for ice water. From then on, the waiter would ask if I wanted my "usual" and bring ice water, which I found funny. But, he treated me asif I was the biggest spender in the place, in spite of the fact that I never spent a dime. So, at the end, I went back up and palmed him a nice sized bill. He gave me an origami bird with the signatures of the entire bar staff as decoration. I still have it.
So, use your own best judgement. Tipping is supposed to be a matter of thanking someone, not etiquette. Keep that in mind and you will be fine.