Common defensive drills include infield-outfield routines and defensive situation drills. Standard, effective offensive drills include batting practice using pitching machines that throw either fastballs or curveballs.
A good infield-outfield routine is an essential practice element for most any baseball team, and is the standard way that most teams prepare immediately before a game. The basic drill consists of hitting a few balls to each player on the field in succession. Start with the outfielders, then move on to the infielders. The idea is to give each defensive player a chance to warm up and practice by making plays that are similar to those they will be experiencing during the game.
Besides standard batting practice, offensive drills that put emphasis on specific aspects of the baseball swing are effective. Hitting balls off of a batting tee is an excellent way to help a hitter develop hand-eye coordination and to practice hitting pitches in areas in which he typically has difficulty.
For pitchers, a good twist on the standard bullpen or pre-game warm up routine is to have him simulate "working a batter." In this drill, the pitcher pretends he is facing a live batter, takes his signs from the catcher, and performs his pitches as he would in a regular game. The idea is to "strike out" the absent batter by executing each pitch accurately. This is a great way to help improve a pitcher's concentration and accuracy. It also serves as an excellent way to reinforce his understanding of pitching tactics, such as "setting up" hitters.