Intuitive and simple keybinds, as well as plenty of player feedback. Example: how many functions can the player perform with WASDNM? Or how intuitive can you get with gamepad controls?
As a completely seperate idea, typing as a skill required for the game. For example: see Helldivers reenforcement system. Missile strike: WASSWDS
Minimization of luck elements (some luck can be fine, but only if the player can counter it easily and it doesn't cost them anything), power-ups, and good use of dynamic input. Dynamic input meaning mouse or anything that's not a button.