Remember that selection acts upon whole animals, so all traits must be taken into account. Finally, most organisms have historical limitations - because of previous changes, future changes are out of the question. Lots of examples of selection oriented organismal change seen in artificial selection .
Selection can act in many different directions.
Important to remember that in reality, organisms are not selected for , but rather, other organisms selected against . For a given trait, a population usually has a normal distribution of individuals with different phenotypes. Stabilizing selection - narrows the distribution of traits. Directional selection - favors one extreme over the other. Disruptive selection - favors both ends at the expense of the middle.