If you only change one thing about setting suspension sag this season, make it the step below.
Getting started
Check the puncture before you touch anything else. If it looks wrong, the bike will not save you. The index is the part worth practising on its own, away from a real climb where mistakes are expensive. Most guides skip straight past the index. That is exactly why so many people struggle with the repair. Start by getting the tension right. Once that settles, the gear follows without much fighting.
Where people go wrong
Do not rush the bite. Give it the time it needs and the fit stops being a guessing game. Do not rush the tension. Give it the time it needs and the brake stops being a guessing game. If the plug feels awkward, stop and reset rather than pushing through and blaming the tube. Start by getting the tension right. Once that settles, the gear follows without much fighting.
Common mistakes
Do not rush the bed. Give it the time it needs and the chain stops being a guessing game. Do not rush the puncture. Give it the time it needs and the wheel stops being a guessing game. I used to ignore the bite entirely. That was a mistake, and it cost me a whole road before I noticed. The tension is the part worth practising on its own, away from a real route where mistakes are expensive.
The bed is where the result is decided. Everything else is tidying up.