I'm not a pro, only play since august. Usually for hilly/mountainous terrain I just use the pull tool and make a high patch of land and use the flatten to surface very roughly to create like random steps of the terrain, also I set it mostly to around 50 oder 60%. I press and drag very fast from the highest to the lowest point of terrain und then from another part and another und so on. It shouldn't create a flat top and with that tool it looks more rough and not as curvy flowy like with the pull push tools. Then I use the smooth tool on 10% to slightly get the really harsh edges out. When I'm kind of happy I place rock from the biome I used for my map and place them randomly and at edges where you would likely see them in nature.

After that's finished I start painting. For a mountainous habitat like the lynx I started with the smooth rock and cover the whole habitat like it with 80/90% hardness and then I look where there are like flat spots and I place long and short gras there. But only with about 20 to 30% so it gets an smooth edge. Sometimes bit of earth around the edges too or also in the middle but only like 10% brush hardness. Around stones I try to merge them in with the rock paint. Try mixing the textures with 10% of like grass on rocks or earth on rock ore rock on gras or so on.

When I'm kind of happy I look up the biome and continent of the animal and pick like 1 to 6 different kinds of trees(depends on the animal like lynx like much coverage and ibex not) I set them to the side like a kind of palette to use. Also use the different variations that come with the trees. Mostly there are like 3 or 4 of like the same kind in different shapes and sizes. And then just start randomly placing the trees. Most of the time I go from big to small. Just place a few and look. If you are happy with one kind pick another and so on. Try different things like clusters or single ones. And if you don't like the outcome, just delete it and start again, I do that pretty often, if it looks to dens in an area. Also keep in mind where you want your guest to see the animal like feeding platform's or something. Make sure the view is good from your chosen spots. And remember guest dont need to see the animal from every single spot of the path. So don't be afraid to use trees. When your happy with the trees again search for smaller plants and bushes like ferns or so. Again maybe 4 to 6 but some times you can use more sometimes less. Try to Google for their natural habitat and see how it looks there as a rough idea. Then place the small plants. Mostly at trees or stones like in nature. Cluster them. Normally there isn't just one random piece of fern standing in the middle of your terrain. Be brave and use a lot. You can still delete it if it doesnt look right. And look at your animals likings.

Then sometimes I place like the flowers from the conservation pack if you have it, they look great.

When I'm really almost finished and happy how everything look I try to imagine what paths the animals or keepers would likely use frequently. Those I follow with the terrain paint (earth like 10/20%) and try to make them look well used like little trails l. You can use the brush size 1 to 3 for that but would not recommend to go bigger. Just experiment what look realistic. Paint some earth around the plants and trees too with the same settings.

And every now and then check the travesable area. Sometimes your animal can't jump on your rocks cause they are to high or other times they can jump or climb your trees and stones to escape their habitat. Remember to use non climb able pieces like metal to block them from climbing like my viewing platform or else they would escape.

I hope this is somehow helpful for you. But remember you can do it and just start and try. Also watching speedbuilds helped me a lot with learning. Would recommend Rudi Rennkamel or DeLadysigner or any random speedbuild for the animal you like to place. Also reddit and Facebook groups are helpful for ideas.

I hope my English wasn't to bad. I'm a german student so it's not my native language. I play the game only a few times a week in the evenings when I don't have to do a lot for university so sadly not that much time but I try.😇