There are a lot of things you don't want to buy used. For example, it's best to avoid used toothbrushes, underwear, and child car seats. However, a used acoustic guitar should not be on this list; in fact, a used acoustic guitar often represents an investment a musician can make.

For example, used guitars have aged wood that enriches the tones and lends a maturity to the sound that cannot be replicated in a new guitar. Another advantage is pricing; used guitars, much like cars, sell for a fraction of the price of a new guitar simply by virtue of having already been taken from the store.

That said, buying used acoustic guitars must be done with a measure of wisdom. Rushing into a transaction just because of price or pressure to buy will likely result in disappointment.

Instead, educate yourself on a few important principles when going on the hunt for a used guitar, and you will be rewarded with a nice instrument that you can play, enjoy, and be proud of for a lifetime. Below are some tips that will help you make a good decision.

Check the Bridge and Top for Stress Damage

When properly tuned, the strings of a six-string acoustic guitar can exercise over one hundred pounds of force on the bridge. Since the bridge is attached to the top of the guitar, the burden is also transferred to this location. Ultimately, these forces can cause serious damage to an acoustic guitar, especially a cheaply made model.

To tell whether the bridge has been damaged, use a credit card to gauge the gap between the guitar top and the underside of the bridge. If you can slip the card in between the gap, then you know the bridge has been lifted and will need to be remounted.

In addition, hold the guitar up to eye level and look across the top of the guitar from one side to the next. There should be no bulging or rounding of the top; if there is any sign of this, then you can suspect the wood has been deformed by the high string tension. This is a serious problem, since there may be no economical way to repair the damage.

Check the Neck for Proper Alignment

Once you have taken a look at the bridge and guitar top, move to the neck of the guitar. The neck's attachment to the body of the guitar is a key point of potential weakness. The neck can be broken if the guitar is dropped or suffers other abuse.

In addition, hold the guitar to eye level and sight down the length of the neck toward the bridge. If there is any twisting or warping, the neck will probably need to be replaced or reworked. This is a major repair that will cost hundreds of dollars if performed by a qualified luthier.

Inspect the Guitar for Cracks or Loose Bracing

Next, you will want to take a closer look for other signs of damage or abuse. Go to a well-lighted location and carefully inspect the body for signs of cracking. Minor, well-repaired chips don't usually affect a guitar's playability, but major splits will need repair, if fixing the guitar is even possible.

Loose bracing can be another problem with some used guitars, and you will want to rule this out before moving on to the next step. To check for loose bracing, gently tap the guitar at all points across its top, bottom, and sides. Listen for buzzing, rattling, or vibrating sounds; the presence of any of these noises is an indicator of loose or broken braces.

Determine Whether the Guitar Is Laminated or Solid

If the guitar is still in your hands, that is a good sign and may yet prove to be a wise investment. However, it is advisable to know whether the guitar is built from laminated or solid wood before making a purchase. Solid wood ages the best and provides the most beautiful tones. It is also a mark of a higher-quality guitar and can help confirm the wisdom of your purchase.

Laminated guitars can still be excellent instruments, so don't necessarily rule them out unless your heart is set on a solid-wood guitar. However, laminate guitars aren't going to produce the rich, deep tones of a solid-wood guitar.

To tell whether or not a guitar is laminated or solid, take a close look at inner side of the sound hole. If the guitar is laminated, the wood grain from the topside of the guitar will abruptly end at the edge of the sound hole.

However, the sound hole of a solid wood guitar will reveal a continuity of the grain pattern all the way down into the guitar.

A used guitar can make a great investment, but choosing a quality guitar does require a little work on your part prior to purchase. However, if you take your time and don't allow emotions to outstrip logic, then you will likely find a real bargain and an instrument that will serve you faithfully for years to come.