Early in my world's development I envisioned the geography in a fairly flat, linear way. The reason was that I have trouble visualizing complex shapes, extending to things like landmasses, cityscapes, etc. So when imagining my various nations, by default they ended up sitting alongside and above/below one another.
By the time I started thinking of my physical world as a continent, everything seemed too small and cramped together. More importantly, the region inhabited by Celtic-like people sat directly East of the region inhabited by East Asian-like and Arabic-like peoples. What's more, I had no idea how far away from one another these regions were and even on paper seemed like I could draw a straight and level line from the westernmost nation to the easternmost one.
Eventually I decided that it wouldn't do to have everyone live on the same continent and decided to put the Eastern peoples (who inhabit the western lands in this world) on a separate continent. However this just changed the problems already present and brought my attention to another one. Concerning the existing problems: How far away can a European-inspired people be from those who are Asian-inspired so that the cultural divide is believable? Onto the new problem: Now that there is a western coast to the continent where the European-like peoples reside, how large should it really be? Also, the Celtic-like people used to reside at the original continent's center before I split it in two. The first name I had for the region was Midland likewise. Is it any more realistic to have Celtic-like people on an eastern coast, beyond which are Asian-like people? And if I'd go with that, how far should these continents be apart? Furthermore, I am still annoyed with myself for placing everything next to one another in a line.
On a separate note, I don't feel like I have enough cultures. First there was just a German-like nation, the Celtic-like one to the west, a Nordic-like people lying north of the German-like nation, and a Mediterranean-like people residing on an archipelago that lay close to the coasts from the north of the continent down to the south. Of course I could always go with each nation having multiple regional differences, but that seems like a cop out. However I also don't like the idea of contriving new nations and people just for the sake of variety.