The fundamentals to know about the leveling system revolve around those virtue points you get each time you level up. When your skills improve enough and you rest in a bed, you'll receive 12 points to work with and they're pretty flexible in how you use them. Major skills progress faster and give more towards leveling, but every skill helps you advance which is nice to keep in mind when planning your build.

The sweet spot is distributing those points across three attributes, with a max of 5 going into any single one - maybe try splits like 5/5/2 or 4/4/4 depending on what you're building towards. Your major skills start with that nice +20 bonus and level faster than minor ones, but don't ignore those minor skills since they still contribute to your overall progress.

The big improvement here is how you're not locked into matching skills to attributes anymore, so you won't end up underpowered against those scaled enemies. Just remember you need to actually sleep in a bed when you're ready to level up and claim those points - pretty important detail that's easy to forget when you're deep in a dungeon.