[peterkos]

As others have said, try to clone something already out there! But start as small as possible.

Like, for Instagram. First, just the scrolling list of images. Then, images with text under them. Then, a tab bar with images and a profile. After enough of this, a basic skeleton will form and you'll start hitting the fun edge cases: how do you edit a user's comment? How do you make sure user data is always in sync? How do you handle every possible API error that you might get, and communicate that simply to the user?

Open source projects are also a great reference. As an iOS dev, I'm biased, but I've heard Android code tends to err on the side of "meh, it works", even in large projects, so be on the lookout for that. Software architecture tends to be fairly consistent across platforms in my experience anyways.