How can I keep track of which outbreaks I've resolved?
I normally place the 4th cube on top of a triangle of the three existing cubes in the infected city. Then, place a cube in all it's neighbours and move the outbreak meter up 1. Move the 4th cube off the stack of three and place it on the board (making a square) to show you've resolved that outbreak. Repeat for any other cities which just received a 4th cube (which is on top of the pile of 3). Once you have finished, remove all the 4th cubes which are on the board.