Hi. Glad to see the interest in eyelash extensions! The author has already made a pretty good list of materials needed. Additionally, I would recommend paying attention to client comfort, for example, using silicone eye pads.As for buying materials, I recommend looking at
https://stacylash.com/ They have a wide range of quality products including lashes, glue and tools that will suit both beginners and professionals. It's also worth reading the reviews on their website - it'll help you make the right choice.
Good luck with your endeavors!