The base is always about 0.7V above the emitter. If the emitter is tied to ground, this is difficult to control. Using an emitter resistor allows you to calculate the bias point much more easily, provides negative feedback to keep it in range, and prevents bad things from happening if the transistor heats up.
For maximum output, you want to bias it so the collector is at 1/2 the supply voltage, 4.5V in the case of a 9V battery.
Here is how you do it.
1. Choose a collector resistor.
2. The emitter resistor will be 1/G times the collector resitor, where G is the desired voltage gain.
3. Determine what current will drop 1/2 the supply voltage across this resistor.
4. Determine what voltage the emitter will be at, based on the approximation that the emitter current is the same as the collector current.
5. Add 0.7 V to the result of step 3.
6. This gives you the voltage you need at the middle of the biasing divider.
7. Choose resistors to give a little more than that voltage, and also so that their parallel combination of gives you a current which is a little bigger than the collector current divided by the beta (current gain) of the transistor.
Then, when it doesn't come out exactly right, adjust the resistors until it does
Bob
Edited to add step to compute the emitter resistor.