Time and space are two of the biggest excuses for not practicing your game. The following video shows you four drills that can be done with two people that don't take too much of either. They can be done indoors or out, so weather is not an excuse, either.
In the first drill, a coach or another player rolls a ball to the left and to the right of where a fielder is set up, alternating back and forth. This drill gets a player moving his feet correctly so that he is in the proper fielding position when the ball arrives.
The second drill is simply throwing one or two hop grounders directly in front of the fielder. It's important to notice that two hands should be used to field ground balls when you are squared away with the ball coming directly at you. As the ball is fielded, raise the glove as if you were going to next make a throw.
In drill three, grounders are tossed to the non-glove side of the player to get him used to snagging a ball across his body with only the glove when there is not time to get squared away. Toss balls progressively further away so that the fielder gets used to how the feet need to work, as well. As a bonus, do the same drill, tossing balls to the glove-side. When he's good at both, switch it up and rotate back and forth.
The final drill uses a rebounding/pitchback net. Tossing balls into the net that are then fielded gives the ball a different spin than a tossed ball - more like the spin a ball has coming off of a bat. After fielding the ball successfully, the player should get into a throwing position. Because this drill involves the use of a rebounder, if you have one of those, it can be done solo, with no other player.
When performing all four drills, it is important to note that the glove should always stay low to the ground. It's much easier to come up to grab a ball than stab down to get it. Also, notice that the fielder's head stays down the whole time as he sees the ball into his glove.
Pitching Machine Stop Quote of the Day: "In theory there is no difference between theory and practice. In practice there is." - Yogi Berra