In honor of my dad's birthday, "MR. G", I present to you "the backhand drill". When learning to play, he always told me that you're only as good as your backhand and second serve. If both or either of those two components break down, it's going to be tough row to hoe. Anyway, the purpose of this drill is to get as much repetition and backhand practice as possible. This is particularly important for juniors who seem to hit forehands day-in and day-out but regard the backhand as a mere after thought. Here's a little tip from an old snake: don't let me catch you with a glaring weakness on your backhand; I don't care how good your forehand may because you're simply never going to hit it (don't even bother warming it up - j/k) or you're only going to hit it from the most awkward positions. I'm not too proud to slice you, dice you, moonball or junk your forehand to get enough of the backhand exposed. So make your backhand rock solid or be prepared to run.
Figure 1: this is a half-court game up to 10, 15, 21, etc. where the players (a) can only hit backhands; (b) the ball can only go cross court unless you go down-the-line drop shot (player chasing the drop shot CAN hit a forehand on that play only). Players cannot hit inside out forehands but can come to the net where they can hit forehand volleys. The point, however, is to stay back and grind with the backhand.
Figure 2: this game is the same as the one in Figure 1 although the players get to use "more court" (i.e., players can hit 2-3 feet in the down-the-line half (deuce side)). The purpose of this drill is to learn how to hit the backhand and recover to the middle (otherwise you get caught with a forehand). This is particularly useful for players who tend to plant themselves 2-3 feet in the backhand side of the court. Anytime you get complacent, a good player is going to take advantage of your positioning so it's always preferable to "stick and move".