Thank you for the welcome,

world mapping in short (skipping transformation of the old maps and lots of fine tuning):

1. I absolutly don't like fractal maps. So i always try to simulate some "real" tectonics.
2. I draw some raw supercontinent in inkscape.
3. I draw enough tectonic plates. Keeping in mind the vectors of tectonic movement.
4. I break the supercontinent in nice parts. Move the parts around the map.
5. Export 2 layers (tectonic borders and flat continents)
6. Import those layers in GIMP
5. Increase or decrease hights (all simple greyscale) inline with tectonic movement. (mountains, etc.)
6. Add some old plateus.
7. Add some random textures.
8. If needed increase/decrease some details in different ways as needed. (small island, very big river beds etc.)
9. create a relief map.
10. add a climat layer and move climate zones to fit wind directions, rain etc.
11. create a cloud layer.
12. export and project on sphere.

I dont use bitmap graphics if I go into more details: Roads, cities, landmarks, notations, swamps, rivers, ice are all added on different layers inside Inkscape.