Before I begin the inquiry in earnest, allow me to express how fascinating I have found this website. The variety of members and artwork is simply beautiful, and I am extremely excited to learn more and view more.

I've done maps in the past--generally quickly thrown together for fun or for a few roleplaying adventures--but have never begun a project hoping to create a world map with realistic geography, and I am wondering if there is a best way to go about creating this. Is there a Determined Order for realistic cartography?

I've currently got 15000 x 10000 pixels of raw coastline to work with. Here it is, smaller and with sort of distasteful salmon-orangey-grey oceans:

Click image for larger version. 

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(The scale is far too small to read and can be found in the bottom left corner. The scale reads up to 1000 km)

What is the next step? Should I begin charting out tectonic plates so I can lay out mountain ranges, fault lines, and rough elevations? Or should I start with elevation and work towards plate tectonics? Should I just do a rough, unrealistic sketch of what I want where, to perfect and realize later?

Thanks for your help!