The MidtownATL.com website has a nice post from someone who “broke up with her car” to become a transit commuter in Atlanta. She includes a good list of tips for new MARTA riders:
Use the OneBusAway app to see when your next bus or train is coming: I now ride a combo of the bus and train and completely leave my car at home. Knowing when the next bus will be at my stop is helpful as I’m deciding whether to make that last cup of coffee at home.
Pack a bag: I packed one and store it in my office. I have a few pairs of heels at my desk since I wear comfy flats on the way in, an umbrella, and a spare magazine just in case I forget my reading material.
Stay occupied: You just freed up so much time by taking transit; use it! My ride is short, so I can read a bit of my book before I get to work. I also love to listen to the PRX Remix app to get my NPR fix.
If you don’t know, ask: Transit riders are very friendly and usually know the system well. If you’re not sure where to get off, how to use the fare gates, etc., ask someone around you. This is Atlanta, and Southern hospitality is real and thriving!
I second all these tips and I’ll also add that, in addition to the excellent One Bus Away app, you can also get full rail and bus schedules, as well as real-time arrival times, on the MARTA On the Go app. I use both.