Knife basics are essential skills for anyone working with drywall. Lydia demonstrates the proper techniques for applying compound to the wall using different knives. She emphasizes the importance of the angle of the knife when spreading mud, as well as the pressure applied for a smooth finish. She also shows how to cut an edge for a clean feathered edge. Tips and tricks for using different knives, like the six for filling screw holes, are also shared. This video serves as a helpful refresher for those new to using knives in drywall work. Remember to thin your mud for better results and don't be afraid to use pressure for a professional finish.