First, look for the source of the leak. And be certain it is indeed,
engine oil, not transmission, power steering or other types of fluid leaking.
1. Oil drain plug...is it tight? Is the drain plug gasket or seal in
2. Valve cover gaskets. Are the cover bolts snug? These should be
torqued slightly, as too much torque can distort the covers and also
cause engine oil leaks. Cover gasket leakage usually messes up the whole side(s) of an engine block.
3. More serious in terms of expense are crankshaft seals, as this sometimes could mean engine removal.
On the other hand, even though it's annoying, one small drop now and then isn't usually a major problem. Just be sure to monitor it. If it gets to where it becomes more frequent, or excessive, have it looked into.
Go Fast, Turn Left!