While we're waiting for this to be moved.
Start small. The #1 mistake is attempting to build a route too big and then becoming disappointed, frustrated and disillusioned with the whole thing. Not saying model RR level, those are a whole other skill, but a small route that doesn't over tax your skills. Learn how to find just the right object for each location in your map so it looks good. Figure out how to place tracks and all of their associated objects to make a route that works.
Until you're comfortable, don't worry about ground elevation. Work in a flat country first.
Depending on how powerful your computer is, avoid the temptation to add every possible object in a small area. Baseboards are cheap, add a few and space out the objects, your GPU will thank you.
And most important, have fun.