If you look at any of the great post players in the game you will quickly realize that they have a great command of the pivot foot. They are able to get the positioning that they want, and then they are able to read and exploit the defender with different pivot moves.
This training video is going to breakdown the technique of using your pivot in the post and then also allow for the player to get a lot of repetitions working on pivoting in the post. Although this drill is primarily for post players, it is still something that can be applied to guards. A great example of a guard that mastered the pivot would be Kobe Bryant.
Drill Name: Pivot Finish Post Drill
Drill Goal: Work on finishing in the post with a pivot.
Equipment Needed: 1 basketball, one pad (optional), one passer, and one dummy defender.
Tips: Stay low and athletic before you catch the ball all the way through to the finish. Check your inside shoulder before you attack and stay under control. Sell your shot fake every time and practice good habits. Make sure that the dummy defender is cheating one way or the other to give the player a read to what finish they are using.
Directions: The post player is going to start on the block with a dummy defender on their back. The passer will start on the lane line with the ball. When the drill starts the post player will allow themselves to get slightly pushed off of the block by the dummy defender as they post up and the passer will dribble over to the wing to enter the pass. The post player will catch the ball, chin it, and check their inside shoulder.
From here you can work on four different types of pivot moves; attack to the middle shot fake step through finish, attack to the middle drop step counter shot fake step through, attack to the middle shot fake double pivot finish, and attack to the middle drop step counter shot fake double pivot. You can work on each of these moves one at a time, call out which move each time, or have the post player try to read and make the correct move depending on how the dummy defender is guarding them.