To sketch any graph look for:
 
zeros;
 
turning points;
 
asymptotes;
 
positive values and negative values;
 
the evaluation of the function at key points, such as $0$, $\pm 1$ or the boundaries of the range or domain of the function (i.e. the possible input values and max/min output values).
 
Also, ask yourself: Does the graph vary smoothly from point to point?