And also at the results and the intermediate steps. Visualize everything. Don't just look at the final evaluation metric but dive in and see where things go wro

And also at the results and the intermediate steps. Visualize everything. Don't just look at the final evaluation metric but dive in and see where things go wrong. Do just a few bad predictions skew your score? What does the best prediction look like? What does the worst look like? Are all your results just shifted by 2 pixels to the left due to some bug? Are there mislabeled examples in the test set? Etc. etc.