For every individual skill level you gain, you’ll get overall levelling experience. Every skill can be levelled to 100, at which point you can choose to make it “Legendary,” which resets it to 15 and gives you all the skill points you invested in perks back. This is because each skill has its own level value, which contributes to your overall character level. However, sometimes you need to consciously level these utility skills if you’re trying to level up fast overall. A lot of these skills can be levelled passively, so you’ll likely net some nice experience by simply playing the game.
While it’s easy to commit to one-handed swordsmanship or Destruction magic, it’s essential that you remember the likes of Sneak, Alchemy, and Lockpicking. First of all, it’s important to recognize the entire breadth of skills in the game.