- Never aimlessly browse through large codebase. Pick a change you want to introduce, maybe a string change, a small bugfix, low hanging feature etc. Goal gives you the motivation to keep digging through things and in that process you make a good mental model of the codebase.

- Sprinkle logging statements all over the place and tail logs to figure out the execution flow.

- Look at the past merge requests. They typically have descriptions. Go through the ones where you have some context about the goal of MR.