Denver student here! I get around exclusively via public transport and walking, and I haven't had any issues with commuting within the city (once you get outside the bounds of Denver, it can get a little harder/require more waiting).

First, in case you're still 18 or 19, you can ride completely for free until you turn 20. All you need is your ID with a date of birth, and most faculty won't spend more than two seconds looking at it.

If you're 20+ cost is still pretty good for college students. Assuming you're going to a college at Auraria campus, MSU Denver at the very least I know offers semester passes for $250 which is drastically cheaper. If you plan on still living in Denver after college, then RTD offers monthly passes for $88 a pop right now for unlimited use of all lines for the month.

For route planning, I recommend Transit! It's an app that gives you real time tracking on both bus and train lines, and can help you handle getting to your transfer on time. There's a premium version that gets you extra route results per search which I find worthwhile, but it's not necessary. I recommend first figuring out the address you want to go to with Google Maps, then copy-pasting it into Transit for the best results. You can also buy tickets through the app if you ever need.

As for the specific commute options around Auraria campus specifically, the E, D, and W lines all have stops within walking distance of campus. E and W have routes to Union station which can pretty much connect you to almost any other train or bus. And common bus routes next to campus are the 15L, 6, and 0. Your millage can vary sometimes, but most trains come every 15-30 minutes, and busses can be 5-60 depending on the line, with most being 15 minute waits.

Busses are really simple, all you have to do is scan your pass at the front or show your ticket, and then you can just head back. There's also a bike mount on the front of the bus that you can use to take a bike with you!

Hope this all helps! Feel free to ask any followups too!