I Installed 3 Smart Dimmers and 4 Add-On Switches last weekend. I have the good fortune of being in a 2015-built-to-code house so the 3-way wiring was as straightforward as possible (Option #1 in the commonly linked reference site): line comes in one box, traveller goes to the second box, and load leaves that box to the 1 or many lights.
While not a comprehensive tutorial or how-to, I wrote about my planning and execution process on my blog:
3-way switching is conceptually strange, and some of the more esoteric wiring patterns don’t help matters. The main obstacle in that Option #3 diagram is that the load round-trips through the second box, so you have to also visit the wiring in the light box to instead route a neutral over there as @Synthesis and @ritchierich point out.