Tackling shaky hands while sketching/inking

If you've ever tried to sketch then I'm sure you've had to tackle the common problem of  having "shaky hands" which tend to ruin the ink work or sketch you are working on. 

Here is a simple drawing exercise to help reduce this shakiness in one's lines and getting more confident with sketching:

Draw these shapes 10 times, as straight as possible and without using a ruler:

1. 3 lines- one about 2 inch long, second half the width of the page, and third the entire length of the page. 
2. 2 arcs- one about 2 inches long and the other half the width of the page. 
3. A wave about 2 inches long
4. Circles and ellipses of various sizes and orientations--basically fill the entire (8.5x11) page with shapes, lines and waves using felt-tip pens like microns/sketch-pens or just a pencil. 

Then draw over them 8 times without making the line any thicker.

Ideally it is done everyday before drawing as a warm up, keep doing this and your inking will get significantly better