The pipet tip tends to drip when liquids like ethanol, acetone or chloroform are used. The cause of the dripping is the high vapor pressure of the liquid that leads to an expansion of the air cushion inside manual pipettes. One way to avoid dripping is pre-wetting the pipet tip. You have to aspirate and dispense the liquid 2-3 times prior to transferring the liquid into your destination vessel. Another option is to use a different pipetting system, the so called positive displacement system. It is without an air cushion and therefore no dripping occurs.