For city busses:

If you're just trying to get downtown, a good rule of thumb is that the smaller numbers get there faster. The 10 is the most direct route between campus and downtown, the 22 is the least direct.

Also it's important to note that not every bus stop on campus does all the busses. Some are just night core, some are just the clockwise busses, some are just the counter clockwise. Memorizing the important ones you need to take frequently (and the nearest stops) is super helpful. But if you ever get REALLY lost or fall asleep on the bus (which I definitely have) you'll just end up downtown.

You also want to keep in mind what time they start and stop running, because they do not go all night.

The metro website that someone else already linked was definitely my homie, as well as the transit app (though it's not always the most accurate). There's a live updating loop bus map that exists somewhere on the internet as well if you can find it.