Most Helpful Girl
Just hang out with her LIKE NORMAL. Be normal. Do not do ANYTHING differently because you are in post-break-up-land.
If she is upset, listen. Just listen. Do not try to "fix" things, because that is not the point when girls voice problems.
This advice also goes for the death of family/friends, or any other form of loss.1
Most Helpful Guy
Play video games with her or go down on her.1