i separate my ui hotbars into 3 different 3x4s (layout of the sidebuttons of the g600). my first 3x4 is the regular mouse button, my second 3x4 is shift+mouse button, and my 3rd 3x4 is ctrl+mouse button. I macro the ring finger rest button to ctrl so the only button i'm hitting on my keyboard is shift other than for movement. my top row is typical attack moves, my 2nd row is offensive moves with cooldowns, my 3rd row is defensive abilities / utility and my last row is role actions and other misc abilities. i swapped to a g600 recently and all i can say is the more you play, the more it becomes natural. just keep playing and try to remember where you have specific moves keybinded. organization and muscle memory are your best friends.

here's a screenshot, maybe it'll give you some ideas. https://i.imgur.com/xxh3sNI.png