On the big industrial scale, (high volume, low grade) look for copper porphyry of Andean type, which should be obvious from general geological mapping.
A crude but novel way of exploring is to dump bits of scrap iron in local streams, then check them out a few weeks/months later to see if iron-copper exchange has occurred.
In order of significance, here are the main types of copper deposits:
So in terms of geological features, I would look anywhere where there has been a large amount of intrusive rock and hydrothermal fluid interaction, and focus on Porphyry deposits. These would show as anomalies in geophysical surveys. On a smaller scale, it really depends on the local geology - there is a certain concentration of copper all over the Earth's crust, but concentrations of copper may not always show as obvious features on the surface...