I've been using this world in my AD&D, 3.5, and Pathfinder games for about 20 years. It has pretty much only existed on paper, but I recently decided to move it into the digital world and give it a facelift at the same time. First off, I wanted it to be a bit more realistic than the one I created in high school, but still maintain the features and distances I used in previous campaigns.
Step 1. I drew the known world (on 8.5 x 11) paper, then added the rest of the world in a manner that fit my campaign needs.
Step 2. I scanned the map using my phone.
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Step 3. This was kinda backwards but, the next thing I did was draw tectonic plates. If I was drawing a new world, I'd have started with plates. Anyway, I used the Procreate app to draw my plates on a different layer than the main scanned image.
Step 4. Next I drew convergent, divergent and transverse plate boundaries on yet another layer.
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Step 5. I drew ocean currents on yet another layer. I probably should have split warm and cold currents into different layers to save me some heartburn, but hey.
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Step 6. I drew global wind patterns. Winter and summer winds on different sheets. Pink are summer and blue are winter.
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The next step will be to finish sketching out the world on Fractal Terrains. I'll post an image of that when I get a rough sketch completed. After that, I'll look at modifying my existing climates and terrains.