Aliens. Lots of aliens.
It's about time we saw Starfleet as it should be, with a much more diverse crew, where humans make up only a small percentage--I'd say no more than three in the main cast. It would allow for looking at situations and problems from very different perspectives, rather than just applying human morals and ideals to them with the belief that they are right.
It would also be able to bring some visually interest characters to the screen, as well as unique backgrounds and story ideas (bland human characters such as Kim and Mayweather did nothing but tick a 'diversity' box which has already been done many times in Trek).
For example, an unjoined Trill woman as Captain, a Vulcan male Counsellor, an Andorian zhen at the Conn, plus a couple of totally new aliens in the mix as well as Science Officer and Chief Engineer. The humans could then fill the XO, Operations and Security roles, with maybe a human/alien hybrid as the Doctor.
Whatever the line up they have to be interesting, with their own stories and drives--not just single sentence descriptions (Kim started off as the inexperienced, in-over-his-head rookie, but that can only go on for a year or two before he needed something more to define him).