Philosophy begins in perplexity: perplexity about what one is doing and why one is doing it in just that way. The aim of the philosophy instructor is twofold: first, to induce such perplexity where students had been complacent and, second, to give students the resources to address such perplexity where it arises in their own lives.
As a teacher, I design my courses so as to emphasize the development of broadly applicable philosophical skills, skills that will persist even as students leave the particular subject matter behind (as most will). These skills include: charitably interpreting texts, recognizing and extracting arguments from these texts, and evaluating arguments for both form and content. More broadly, I encourage my students to engage respectfully with ideas with which they disagree, and to questions ideas they are inclined to accept.
Philosophy is a collective, not a solitary endeavor. Both in and out of class, I encourage my students to work together to discover truth (or at least avoid error).