One thing I think would help a bucket load would be to make the grenades much more visible, I mean the grenade-danger indicator is pretty poor at indicating where the grenade actually is and where you have to go to avoid it.
You don't know if you are far enough away till it is too late, you can't see it till it has landed on the ground.
What would help a bundle is if the grenades were glowing and bright, as if there was a flashing LED mounted on them or a there was some HUD based overlay. And along with that a beeping noise for any armed grenade, people are able to avoid enemy gunfire, especially if they use headphones or surround-sound speakers, this would be fine for grenades. The beeps could also increase in frequency as the grenade timer counts down indicating how much time you have.