There's one thing key to calligraphy: pen angle. Not pen width; pen angle.
One easy way to talk about this is if you take two pencils and rubber-band them together so they come to two points. Kind of like chopsticks, but with one or two rubber bands. Hold them in your hand exactly as you would a regular pencil.
As you touch down on the paper with this double-pencil you will be dragging it along and drawing and experimenting with letters and doodles and of course you will quickly see the double line it makes.
If you lay the two points on the paper and turn them, that's when you are making different pen angles. This term only refers to the angle of the pen-tips in relation to the top edge of the paper. This is not a reference to your wrist movement, or to the angle of the pen itself in relation to ANYTHING. Only in reference to the angle of the pen-tips to the top edge of the paper: thus you can have a 30 degree pen angle or a 45 degree pen angle - the most common beginning pen angles in calligraphy. Try it!