Like previous editions, 5e possesses a list of skills that players can choose to help further define their character's specific training and areas of expertise. The list is rather short, only possessing 18 broad skills with multiple applications. While I personally prefer shorter skill lists like this, I understand why others would want a more detailed one.
With that in mind, I started to toy with ways to create a nice middle ground between these two camps. After some serious brainstorming, a light bulb popped on inside my head: why not create a way for characters to specialize within certain areas of their skills?
Keeping with the spirit of 5e, the rules for this should remain relatively simple. During character creation, players may choose to expend one of their skill proficiencies to gain a specialization in another skill they are proficient with. The specialization is created by the player from scratch, with the Dungeon Master possessing the ability to veto any specialization she feels doesn't fit the nature of the game's setting.
When making an ability check that deals with on of the character's specializations, they receive advantage for that roll. My reasoning for this is that a specialization represents you possessing an advantage with a certain aspect of a skill. Thankfully, 5e has the advantage/disadvantage mechanic and it feels like a natural fit. If you'd prefer another kind of benefit, you could reward a flat +2 bonus or double the character's proficiency bonus. Either would probably work fine.
Here's an example of how this house rule would work. Let's say you're trying to create an elf ranger who has sharp hearing. You decide to expend one of your skill proficiencies to give him "Hearing" as a specialization associated with Perception. While he can make Wisdom (Perception) checks as normal, he is especially adept at hearing things and receives advantage when doing so.
I feel like this'll be an interesting compromise, allowing those who want more detail to have that while letting those who prefer the more broader skill list to ignore it. Yes, those who choose to select specializations will get advantage, but only in specific situations. The next time I run 5e, I'll probably be implementing this rule and seeing how it works. Feel free to use it as well.