I am also a novice here (and into mapmaking), Cradlis, so I don't know if I will be able to help much. First I liked your coloring, simple but good, the gradients and all. As for the mountain size, I don't really know it. I mean, you made then as in topographic maps and those usually have a legend in order to indicate de altitudes that each line represents. So each line in your map represent a difference of how much altitude, a 100, a 200 meters? I would start by thinking about it, look here is a link that may help: https://digitalatlas.cose.isu.edu/geog/basics/topo.htm

Also they show this example:
Click image for larger version. 

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