As Viking said, you can go about it in whatever way feels right to you, what matters is understanding how everything works and ensuring it makes sense. On my fantasy world I first started with the continents and then added the tectonic plates. I'm currently remaking it from the beginning, and started with the tectonic plates first this time. Either way worked fine, and gave a pretty similar result for me.

The most invaluable resource I've had for making the world is the Climate Cookbook. Once you've worked out the coasts and mountain ranges/high altitude areas, that link shows you how to create a realistic climate. Also, there are a few other threads in this sub-forum with people doing the same thing posting updates regularly, take a look at them to see what they're doing if you feel stuck - that's what I do! One thing to note is that if you want to be able to create a 3D globe or other projections of your world (in Photoshop, G.Projector or Google Earth), the initial map needs to be equirectangular, i.e. two times as long as it is tall.

Looks like you've made a good start though, it'll be interesting to see how this progresses