Here are a couple of items that I wish that I had picked up earlier. They are not required, but they greatly simplified my life.

• headlamp: Trying to balance or prop up a flashlight while working used to result in so much frustration.
• tin sheers: I love these so much that they have replaced scissors in most day-to-day applications
• flexible drill bit extender: So many screws are in places inaccessible to a drill body. This inexpensive item solves that problem. Magnetic wristbands: Keep those screws and bits from getting lost.
• level that is at least 2ft long: I really appreciate having a level that can span two studs (16")
• precision / mini needle nose pliers: I don’t need them often, but when I do I am always happy that I have them
• painters tape: I am surpised how often I use painters tape for all sorts of applications

It’s easier and generally more acceptable to ask here than in the grocery store.