Well, when I started down that path, I found Francis Lansetti ( signsofgold.com ) and printed and read every article that he wrote for signs of the times mag... and was lucky enough to meet him at the Atlantic city sign show. I stood and watched and asked questions for several hours...
Tools. 1. Guilders knife. 2. I made my own guilders pad (a piece of Dibond with a thin pad of foam wrapped in tee shirt cloth) . I have a giulders brush, and use it about 1/2 the time. Burnish brushes - a set of makeup brushes from target (ELF is the brand). Kaolin powder. And I bought a tool box that is giulders supplies only!!! No paint, and it is kept in my office, and not in the shop. I have both fast and slow size.
The last time I bought gold, I got it from sepp leaf. I was getting a cheap gold from somewhere else, but I don't remember off hand. I did get some off eBay, and it was utter garbage... not really a gold, more of a foil....so unless you know what your getting, go with a known gold leaf supplier.