If its gonna be mini you might as well use more plates and put more effort into shaping the island and flat terrain. It looks ok right now but there's multiple things you could do to improve.
1) Stop using 2x wide plates and bricks. It severely limits the detail level, and since this is small scale, there's no reason to do that. Don't be afraid to "spam" 1x1 plates in order to get the look you want, again, since this is small scale.
2) The terrain design itself is a bit unrealistic but passable, I guess. The volcano needs to be redesigned to utilize more steep changes in height, to signify it as a mountain rather than just a high hill. Points on the large cauldron, though, which is about the right size and with extra shaping (rounding off, etc) would be perfect. Also consider extending the mountain/volcano so its more like a range rather than a pyramid placed in the middle of flat terrain. See picture:
As you can see, its not just a single peak; it runs along like a crest. Unless your volcano is meant to be a cone, I think this design would look better.
