Well, first, you have to make the bases: a single jungle tree, a few varieties of plants, etc. Just copy and paste them all over the landcape to make a varied jungle.

Thanks for the tips dude!

Sure!

use the railbricks magazines in this link for some ideas and help
https://brickmodelrailroader.com/index.php/download-railbricks/

Dear BrianTheFireLord,

For a mountain, build an X on the ground and start making an uneven circle around it out of mountain coloured bricks. Then, make a slightly smaller uneven circle on top out of mountain coloured bricks. Continue until you get to the top.

To see this technique in action, check out my Mountain Race models.

Yours,
Hectorking