Do you want to know how to start learning to do all of those things? Easy, take a drawing class, then a life drawing class and then a painting class, or all three at once. You'll paint people, landscapes and still lifes by the dozens.
Why would you want to sketch some naked fat dude or old woman in life drawing class? Because if you can't do that then you can't draw heroes either. If you can't paint the skin of an apple you probably can't successfully render the skin of some barbarian babe's butt. If you can't draw and paint common objects like bowls and vases you'll really trip up on robots, spaceships and armor.
Nor could you draw all the other people who inhabit this fantasy world where heroes can be a hero. There has to be fat old people in a fantasy world, otherwise everyone could solve their own problems, no heroes needed.
And fantasy worlds need...you know...a world. You have to be able to paint landscapes, trees grass flowers and rocks so the hero has ground to stand on. One of the easiest special effects to paint (and it's by no means easy) is clouds. If you can't do clouds you'l never handle smoke, lightening or fire.
Besides all of that there's bowls of fruit in fantasy worlds, where do you think I painted this one? In fact I had a very difficult time painting this scene because Conan the Barbarian kept walking by and eating all of my grapes.
16" X 12" Oil paint on Recycled Board