Because of variation, we have statistics. When all is the same, there is not much to consider. Differences make life interesting. Thus, to think statistically we must give much thought and consideration to variance.
A key step often overlooked by time-poor and assignment laden students. However, as a tutor, I highly recommend you invest pockets of time across your day to reflect on your class and textbook learning about dispersion, variance, standard deviation and standard error. As these are interlinked concepts to describe variance, investing time in thinking about, practising and applying your learning of them will speed and deepen your understanding of stats as a whole.
Below is my Variation PowerPoint I put together a few years ago as a resource for my psych n stats students. I draw on a straight-forward paper by Wild (2006), The concept of distribution, to illustrate the value of focusing your revision on understanding variance.