Hair is an essential part of our overall appearance. It frames the face, suggests a mood, and reveals something about the person’s style or personality. For individuals with medium-length hair, it's often difficult to find the perfect balance between style and functionality. However, there are certain medium-length hairstyles that one should avoid, and today, we will discuss them.

Before embarking on this journey, it's important to clarify that different shapes, cuts, and hairstyles work for different people. Everyone has unique hair texture, face shape, and personal style preferences. However, there are particular styles which may not look flattering on most people or could result in hair damage.

It's also underlined that these hairstyles could indeed look fantastic on some individuals. If you love wearing one of these styles, the objective isn't to discourage you. Instead, the goal is to provide insight into potential issues that may arise from these hairstyles and how they can be avoided.

1. Over-layered Ends: The first up in the catalogue of medium hairstyles to avoid is having too many layers towards the end of your hair. While some people believe that heavy layering at the bottom thin-ifies their thick mane, it often results in an overall thin and unhealthy appearance, especially as the hair grows out.

More often than not, a subtler, less extreme version of layering would ensure the thinning of thick hair without causing it to have a sparse appearance.

2. Front Layers Cut Too Far Back: The second hair faux pas is when the front layers are excessively cut back. This often leads the eye down, following the layers towards the back, rather than lifting the shape up. The idea is to balance the layers in the front and the back for a cohesive look rather than create a visible disconnect, something akin to a mullet. Therefore, ensuring that your layers start behind your ears can help prevent this imbalance.

3. Short Crown, Long Front: The third medium hairstyle blunder is when the length and layering at the crown are shorter than the front layers. The result is two different haircuts melded into one, often looking akin to a long bob with additional hair at the bottom. To ensure better harmony in your hairstyle, try matching the shortest layer in the front with the shortest layer at the top in the back.

4. Disproportionate Top Layer Length: The fourth common mistake in medium-length hairstyles is having the top layer disproportionately short compared to the overall length of the hair. As the length of your hair grows, it's essential that the top layer's length grows accordingly to maintain balance.

Without this balance, the hairstyle can easily start to resemble a bob, giving an overall square appearance which may not be flattering for all.

5. Straight Across Bangs with Unlayered Front: The fifth and final hairdo to be wary of is having straight-across bangs with a pure one length, unlayered front. While some may find this style appealing, it often makes the face appear broader and squarer due to the sharp horizontal line these bangs create. A slight soft layering, or a bit of height at the crown, could be a more favorable approach.

Even a little connection between the bangs and the layers in the front adds a point of interest, a more flattering balance, and a cohesive essence to the overall hairstyle.

In conclusion, it is not about adhering to strict rules, but more about knowing and understanding the effects particular cuts or shapes can have on your overall appearance. Sometimes, a minimal adjustment to a favorite style can bring about a considerable improvement in your look. As with any fashion and style-related advice, the most important rules are to listen to your instincts, experiment, and ultimately, be comfortable and happy with your look. Keep in mind that although these hairstyles can sometimes be unflattering, there is always room for exceptions and personal modifications.