It's helpful to put a rubber band on the jar to mark where the sourdough starter is so you can see how much it rises and falls throughout the day. Here are some other notes on tools and ingredients:
I used all-purpose flour, which as you'll see in the coming photos wasn't ideal and slowed down my progress immensely. Most recipes recommend using rye or whole wheat flour (or a combo of those with AP), which I eventually switched to and it made a big difference.
It's important to use filtered water as chlorine can kill or slow down your starter (you can also leave tap water sitting out overnight). Use cold water if your home is on the warm side, and use room temperature water if your home is on the cool side.
A glass jar with straight sides is easier to clean and important so you can see the starter activity. (These Weck jars are extremely popular for their shape and the ability to easily remove rubber seal and just set glass lip on top.) Cover it with a tea towel or lid loosely sitting on top of it; you want to prevent critters or debris falling in it, but it needs air flow.
A silicone spatula is extremely helpful for mixing the starter and scraping the sides of the jar (plus it's easy to clean).
A kitchen scale makes things 1,000 times easier and more precise. I didn't have one until the end of the process, so I'm putting the measurements in here in cups to start.