Only half-serious, as opposed to 3/4 serious. Take of it what you will.
- Update your gradle and mappings. Get it wrong because you forgot to add the branch name.
- Commit so you feel good about taking the first step
- Rerun setupDecompWorkspace, refresh Gradle project in your IDE.
- Try to compile the mod and cry after seeing the error count
- Easy renaming time. If a class (or method/field with distinct name) has been renamed, just do a global find/replace. Congrats, you just added 10000 lines to the diff. Commit.
- Easy method signature time. If a method has changed arguments, say to add a hand parameter, just do a global find/replace. You DID name your parameters properly, not p_10101101010_xxx, right? ... Oho, you're going to have fun. Commit.
- Easy semantic stuff. This is stuff like changing x y z args to BlockPos, ForgeDirection to EnumFacing, etc. Commit per change.
- Missing methods. If something you override from vanilla is no longer there, first check the bot to see if it got renamed (!mh