I buy a calendar at the local Sefarim store. I think it’s called “itim l’binah”. It’s very good – it has a lot in it, and I think it’s very reliable halachichally. It has a lot in it, and it looks like it was well-researched.
I use it for candle lighting time. For the end of Shabbos, I just add on 72 minutes from shkiya.
I also use it for shkiya during the week, so I know when I have until to daven Mincha. I use it for alos hashachar in the morning so I know what time I have to wash negelvasser and say brachos when I am up all night, and I use it for netz so I know what time I can daven when I am up all night. When I am not up all night, I use it for Chatzos so that I know what time I can daven until.
It’s also useful for checking when Rosh Chodesh is and if there is Yom Kippur Katan that month before Rosh Chodesh and if so, what day it is.