When you're just getting started it can be confusing to know what tools you may need to create certain technique. Hopefully you have a few already in your cake decorating stash and won't need to get too many extras! I've highlighted the bare minimums you need to do each stencil technique, and then some extras. Most of the items are available in the shop and can be found here: Lustre Dust Tools | Royal Icing Tools | Airbrush Tools
For those that are not, I have created an Amazon Storefront as a reference to list the cake decorating tools, books and baking bits that I personally use. It is an affiliate page, which means I earn a small commission off of sales on it, but you are under no obligation to buy & can simply use it as a reference.