Welcome, ravenbow. Maps in the introductory post - way to go. That's worthy of reputation.
You do decent work already - can't wait to see you develop better chops, with good tools in hand. Do you already have some of the more capable graphics packages in hand? You don't even have to spend money - the Gimp and Inkscape will do much of what PhotoShop does. and there's tutorials here that'll accelerate your progress. Or if you have access to them, there's scads of commercial apps that get marvelous results, for differing effort and cash outlays.
If you've been thinking about this over twenty years, I assume you've got ideas galore, lacking only a way to put them down on paper (screen) ? That's really the hardest work, the worldbuilding behind the map. Look up some of the WIP threads where cartographers have explained their thinking as they went - search for "Ysi Earth II", for one. Once your ideas have gelled, a diligent application of experimentation and tutorials will get you something between "perfectly servicable" and "awesome art".
Again - welcome!