I use this trick to stop the feet from sliding when I am animating.
0:00 Understand how the Pegs affect the rig
0:49 Example 1: The Wrong Way
2:08 Example 2: The Correct Way
3:02 White Pegs Explained
3:47 The Result
4:24 Example 3: Planting the Hands
5:34 Plan Before You Start Animating
5:47 Maaarllloooo