The Tips in detail

 "Doing the landscape: elevations"

To get the elevations done you can use the displacement modifier. Applied to a box this will give you the tool to make up the hills and valleys. Where you have to make up your mind is the point, wether you are going to modify the terrain's characteristics intensely or if you just need "some kind of terrain to be there".

In the case you want to do a terrain that has no real-life counterpart you can use noise applied to the displacement. The drawback here is that you can't modify the exact shapes, since the noise is generated by random.

To have a terrain done that shapes exactly like you want you will have to draw your own displacement-map as a greyscale image in eg. Adobe Photoshop. The theory of this technique is quite easy: white means high elevations, black no elevation. Really doing such an image can be a pain, since you will switch from Photoshop to Max and back a whole lot of times until you have what you want.

Using the noise-displacement is much more easy and gives you alot of parameters to play with so you still have a large range of controlling the shapes. The trick is that you should combine several noises into one map and adjust the paramters of the individual noises properly. You will have to try out what kind of noise (standard; fractal or turbulence) fits best to your needs. Also the High- and Low-thresholds within the noises are worth some trying since they rule the amount of valleys and hills and their spacing and much more in your terrain.

You will have to use loads of faces on the terrain or else it might tend to look clunky. Doing the basic shapes it might be enough to use lets say 75 x 75 intersections, but doing the finals you might need to push these up to their maximum 200 x 200. Since the amount of segments is limited per object, you might need to design each mountainrange as an individual object.

To have the mountains built with a general fall-off to the terrains zero-level, you will have to combine the displacement with a black-to-white gradient.

To improve your landscaping skills even further, you can also start modelling your entire geography from a shape or a patch or a mesh. This is fun, too. But to get the starting steps done you might start with a displacement. After you have a start, convert it into an editable mesh and modify where you consider usefull :)

Be aware: playing this game will take hours and can prove to be instantly addictive!