The abolute minimum.
1- The 'have a go' mind
2 - Developing tank
3 - at night under the bed clothes to load the film
4 - chemicals , developer, wash water, fixer, wetting solution for final rinse.
5 - good thermometer
6 - watch with second hands
7 - water
8 - pegs to hang film up with

The temperature is reasnably important, but untill you get to be a perfectionist then it will work if you are a couple of 'C out

You can get it right FIRST time. Follow the instructions.

If you do not try, you will never get it right. The above comments are how I sarted 39 years ago. Yes I have progresed and have, in my time, processed colour slide (both singularly and 12 rolls at a time), colour print and printed black and white and colour neg and reversal. I learnt by reading but most importantly doing it. Do not be put off by complicated comments on how it can all go wrong and a vast amount of equipement needed.