In regards to the tectonics honestly I'd draw the landmasses you want, and then fit the tectonics to them, and then after that change any land forms that theoretically don't fit the way the tectonics would indicate. After you figure out the landmasses you can work on the climates, but Azelor is probably the best here to advise how to take that from simple to detailed/complicated.

As with anything just always remember with everything simple first->detail last. In terms of regions just work on one country at a time as they pique your interests, then one step at a time your world will slowly fill up.