Realistic sketches are the goal for many artists. In the tutorial below, the artist explains how to make the sketches look more real. Firstly, he gives us notes that we should always draw a volume and contour the lines. Secondly, the artists should make the edges more round. In addition, it is very important to put the right weight on the lines, and emphasize the bottom line.
Realistic Sketches in Industrial Style
Whatever technique you decide to chose, the tutorial will guide for the basic steps. But the tutorial will not make you a great artist. You should learn from it, and practice a lot.