Personally, I think a great many people overstate the complexity of fugue writing. It is as simple or as complex as you want. The rules you choose to follow or not follow are up to you. There is a great difference between an atonal fugue and one by Bach, and indeed one by Bach and one by those who preceded him. Why not start by listening to "So you want to write a fugue" by Glenn Gould. I guess what I'm trying to say is that "fugue" means a great many things to a great many people. What it means to you is up to you. Essentially you have a melody coming back again and again, and thats it. Yeah, the opening is a little formulaic, but even then you can vary a great deal - the order of the voices, real or tonal answer, how soon the voices enter after one another, etc. So I would just dive in and see what you come up with.
I've written quite nice fugues (I like them) early on that are way simple, probably break loads of rules, but as I learn more and more, it gets more and more complex. Early fugues had not much idea of harmonic progression, they were simply based on species counterpoint. Bach's fugues had a great mastery of harmonic progression, but also modulated all over the place thanks to the new well-temperament system that earlier composers didnt have access to. Some fugues use highly complex stretto and inversion - others dont. So in short, its as simple or as complex as you want it to be. So my best advice is "so you want to write a fugue, you have the urge to write a fugue, you have the nerve to write a fugue, so go ahead, just plunge right in and write one"
You are not going to compete with Art of the Fugue on your first try - so dont try to. Just start.