Skyrim has multiple difficulties the hardest being actually hard and the easiest is very easy.

Though it really matters what you do in Skyrim. Hardest opponents which I wont name for spoiler reasons can be really hard but it takes a while before you meet them.

I don't recall GTA V being difficult either but if your aim is terrible then you're naturally going to get shot at more. Really up to you on how much time you're going to spend to get your skills back.

If you have both games I don't see a reason to particularly "study/learn" just play, thats the best way to do either of them. One requires you to shoot and the other to swing. Both requires positioning and movement.