@Inge-Permentier , You don't sound like an idiot at all! Talking things out & asking for advice often helps us figure out our own thoughts. It's really tough trying to figure out what to do. Especially when you add the pressure of wanting to make a living on it.
You said that you want to develop artistic skills, and you want to build a portfolio. I think it was in one of Jake's videos that he shared a quote--something like: "The obstacle is the answer." Not having a portfolio is an obstacle, so the answer is creating one. You only get better at something by doing it. As you work on each new piece for your portfolio, your skills will increase.
If you subscribe to SVS, try watching Lee's class, "How To Discover Your Style". (If you haven't already.)
Maybe go back to the Slowvember questions, and try to answer them without thinking about what you want to do for this specific project--just answer them as if a friend asked you in a conversation.
For example, a major theme that is important to me in my life is peace (within myself--world peace would be great & all, but we have to start with ourselves). This is true of the outlook I try to have in general, and I find that I resonate with peaceful images, and calm colors.
What is something that drives you in life? What types of images, entertainment, activities, people, colors, lifestyle, philosophy, etc. are you drawn to? What type of person are you? What makes you happy? What kinds of emotions are important to you? What makes you feel that way? What is it you like about comics and the kind of art you want to create? What motivates you to make something? Try to open yourself up to exploration without obligation. Just jot down a bunch of words, and maybe something will surface. Either way, introspection is beneficial.
I hope this helps!