# Guide to sketching graphs of basic functions

I'm taking a test soon, where I would be asked to sketch graphs. I wonder if there is any kind of guide or general tutorial on the net how to carry out sketching. For instance I would much like to know how would you sketch $f(x)=\frac{ln (x)} {x}$ and $g(x) = \frac{e^x}{x}$ or in general if I have a function $f(x)$ the graph of which I know, how should I sketch $f(x)/x$ or an even more complex question:

If I am given the sketch of two functions $f(x), g(x)$ how may I sketch $\frac{f(x)}{g(x)}$?