Salutem

Here is a height map for one of my continents that I've been working on the past couple of weeks (will do a world map version once the whole world's topography is complete )
Any advice on how to get the mountains and especially the lower hills to look more realistic would be much appreciated!

The continent is called Kilanna, lying on the planet of Mirabilis

Click image for larger version. 

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As can be seen above there is a sharp divide between the low-lying valleys and small hills of Northern Kilanna with its many islands and large inland sea and the rough mountainous terrain of Southern Kilanna. Two very long andes-like volcanic mountain ranges stretch from west to east, bisected by the planet's second largest collisional mountain range. I've not modelled the climate yet (waiting to get all the topography done before I do) and so haven't done any rivers etc. yet.

Made in inkscape using the wonderful atlas mapping tutorial by Artifexian on youtube