How many cells should I put in each tube for my experiment? What should the volume be?

Under ideal circumstances one million cells per tube for analytical experiments is standard. Under many situations you may not have the luxury of that many cells for each of your controls and experimental samples. The minimum number of cells required is going to vary based on your needs, for very simple experiments you many only need tens of thousands of cells. Multicolor experiments that subset out small percentages of cells may require several million cells per tube in order to acquire appropriate numbers of the target populations. You'll want to have a minimum of 300 ul volume in your samples.