I think that you know now enough so that you can go on without farther advice. Just continue and you'll see what it gives. Then do a second map etc.
For the mountains think that often less is more - the ranges look quite OK now (with some hills that make the transition from the edges of the range towards the plains).

Perhaps one last remark.
Without intending it you just did a great river. Take the cliff in the lower right corner, remove the vertical lines, color it in desaturated light blue, add a few tributaries in the same style, connect the lower end to the low right fjord and you have a perfect river even if it doesn't taper much.