Look at the object and figure out how it will be located on your paper. A card board cutout in the shape of the paper will help. Also note any edges that will show space next to it.
Lightly draw the outside edges of the object first. Once you have those proportions correct, fill in the edges on the surface of the object, if any exist. Once the outline is in place, draw darker lines over the object edges next to space to indicate depth. That will get you a basic sketch of an object. This will get you a simple image. It takes some practice and don't underestimate the amount of time you need to simply look at the object. About three quarters of the work in sketching and drawing is actually seeing the object, and not drawing what you think the object should look like.