For this first style, draw each mountain individually but draw them along a rough line to create a mountain range as mountains don’t generally stand on their own. Your first drawings of the mountains are the outlines or the silhouettes of the mountains, next add some shading to your mountains for detail. The shading should always be on the same side of the mountains.
For this style, draw the mountain range with one continuous ridge-line. This should go roughly backward and forwards but can be in whatever shape you prefer. Next, add lines flowing down from the peaks and range line to create the mountains. You can then add some smaller lines, following the direction of the others to add creases and ridges in the land. This also gives your mountain range a bit more detail.
This last style is very similar to the previous style. The difference is that for the second step, you should draw some of the lines running down from the ridge-line with a small fork at the end and then add the accent details.
I’ve also done a tutorial on drawing top-down/birds-eye-view mountains!