Haha I don't mind questions! I'm not sure where your skill level is at, but if you're just starting to look into concept art as a profession, make sure you have all the basic stuff down first in terms of general principles of art (form, perspective, anatomy, color, value, etc.). From there sky is the limit in terms of what you can draw/paint! I highly recommend picking up James Gurney's Imaginative Realism and Color and Light books. They're a must have for any artist and super cheap!
The design part definitely takes years as you want to just draw and observe as much as possible to build that visual library. At work I usually make several different iterations of the same concept playing with shapes, colors, materials, etc. I should probably jot my process down in further detail somewhere lol.
If you need a place to start, just start with the stuff you love and are inspired by. I've always liked fantasy and sci-fi stuff, so a bunch of the material I look at and refer to are just straight out of video games I like playing.
I know this is kinda vague (sorry!), so if you have any more specific questions, I'd be happy to answer!