How Does One Handle Heat Dissipation in a TO92 Package?
TO-92 isn't meant to be a high-power-dissipating package. 180°C/W isn't going to get you too far, and there often isn't exposed metal to help get heat out. 

That being said, there are some slip-on heatsinks available that can get you a few more milliwatts. Other techniques include drawing heat through the legs into the PCB, having a copper pad on the PCB and lead-forming the device to be bent over and touching it (with a clip and some thermal compound). Improvement to 60°C/W is possible.

Having some airflow helps too - a small fan can improve the power handling of the device (especially when combined with a heatsink of some form).