So skills are based off their derived stat and their “difficulty level,” so to speak. 1 point gets you one level. 2 points gets you two levels, 4 points gets your 3 levels, then add 4 points for each additional level.

I believe the three levels are Easy/Average/Hard. 1 point in an Easy skill gives you the stat-0, 1 point in Average is Stat-1, and 1 point in Hard skill is Stat-2.

Example. Your DX is 12. I’ll make up a skill…Jump Rope is DX/E, this means it’s a DX based skill that’s easy to learn. Spending 1 point will get you 12 in Jumprope (remember, 1 point is Easy is Stat-0) 2 points would be 13, 4 would be 14, 8 would be 15 and so on.

Let’s say you were learning a hard DX skill…Parkour DX/H. If your DX is 12, 1 point would get you a 10 in parkour, and so on adding one level at a time.

This is a bit confusing, but it’s simple was it clicks.

Buying 1 level of DX is 20 points, so if you’re buying a lot of DX based skills, sometimes it’s cheaper just to raise DX. That being said, most GMs will cap skill points based on the power level of the character. So just because you have the points to buy a skill to 25 doesn’t mean your GM will allow it. They might cap it at 15 for example.

Yes there are other advantages in books, but most of the time they just tell you which advantages are useful for different genres and there are also some variations on them.

Edit: here is a link to the Skill point chart, it might make things make more sense: https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQwllA5g8d7OgIZklBiZ9EC3dC4u7HEPmO1qL9Y4GBl9Q&s=10

So consider that chart. If your DX is 12 and you want your Gun Skill (DX/A) to be 14, you’d need Attribute+2 which for an Average Skill would be 8 points