My favorite triangle loom supplier is Spriggs Looms and Supplies. She has spent lots of time weaving and perfecting the art of sharing her knowledge and refining looms and tools for the art. My favorite tools are below! Tell her that I sent you.
First item on the must-have list is the loom itself (and I would highly recommend the stand – this is quite unwieldly without it).
Second (and equally important as the loom is this incredible hook). It has a deep crevice for your yarn and a pointy tip to weave in and out of your warped yarn. It is also flat and sleek! It’s called the Snipes Wooden hook tool on the site.
Even just scanning this book, I have learned SO MUCH. I highly recommend the purchase. While expensive, it will take your weaving to the next level.
Lastly, get yourself a basic notebook. You can take notes from the book and use it to plan your projects. Grid dots are wonderful in this book for all things fiber art!