Many training tools claim to improve your swing. Some are effective and others fail to live up to their hype. In my experience, the one tool that I recommend above all others is the one-handed training bat. This is a short bat, ranging from 20 to 25 inches, whose shorter length and lighter weight allow you to swing with one hand (hence the name), working each hand independently.
The short bat shortens your swing path, helps you keep your hands inside the ball at contact and reinforces proper technique. Small bats can also be used with two hands to teach young kids proper technique without sacrificing form due to strength and coordination issues.
Many different brands offer one-handed bats, which are typically priced between $22 and $35. I recommend the Rawlings one-handed bat (buy it here), which we have found to be a high-quality and wallet-friendly option.
Once you get your one-handed bat, step into the batting cage or onto the field and start honing your swing. Great drills to start with include traditional soft-toss or tee drills. For additional options, check out these easy hitting drills.