It's hard to say as it depends so much on the situation, just you assaulting, team assaulting maps, smoke etc.. But some general ideas/rules I have.
- This is not Counter Strike or DoD (thank god) so remember that crawling for 15 seconds is perfectly fine if the nade you finally throw works. Might sound a long time, but it's still way shorter than a 20 second respawn timer plus the time to walk back to the postion.
- If you're by yourself, wait for backup or some other kamakazi idiot who charges blindly
. While they are getting mowed down do your charge and toss a nade. Also helps to sidestep while charging.
- On the being nicer side of teamwork, if you see someone whos going to blunder into a strongpoint, just shoot at the wall hiding the enemy. They usually get the message someone is there.
- Overwatch/support. If people are advancing, get a braced spot to shoot anyone popping up from cover. If people are already setup in shooting positions, don't setup beside them, push on and then setup youself for them to push on. Seeing a team roll this way can be rare, but a dream to see.
- Angles, remember that in the game people only see ~45 degrees left and right (more for wide screens), not the ~90 you get in real life. So as long as you're not right in front, you can get away with a lot more than you would in real life.
- Quick charges, if you've just taken a strong point chances are the enemy are waiting to respawn, CHARGE the next point before they get time to setup. If you get there first you might get 3-4 easy kills as they blunder in expecting it to be clear. This is one of the biggest mistake when not done on maps like Gorlitz (great assault map).