I encourage undergraduate students to see their studies as both exploratory and vocational. A liberal arts education allows students to explore a number of subjects. I suggest they also develop a marketable skill that can be identified in a black and white sort of way on a resume or in a cover letter: I speak X language, I can use X computer program, I can play X instrument, I am trained in X analysis.
Some suggestions for the vocation include: economics, statistics, any language, GIS, STATA or survey methodology. Ideally, a student may be able to develop two of these competencies: both a language and a skill.
Political science majors are wise to realize that while courses in PS will develop critical thinking, reading and writing skills, it will be difficult for potential employers or future graduate programs to evaluate skills of this nature. A piece of published writing, participation in a research project, experience designing and maintaining a website or any number of experiences or skills may signify both your interests and your capabilities. I suggest PS majors to supplement their studies with a minor, a second major or a substantial marketable experience.
A note on study abroad: I think study abroad experiences are invaluable. I also think it is impossible for a potential employer or graduate program to differentiate between a program where one hung out with a lot of Americans and drank a lot, or a program where a student seriously engaged in another place and language. YOU must do the work to demonstrate the value of your study abroad. Write a piece for a magazine, newspaper or undergraduate journal, keep a blog, complete a service project that has real results for real people, take a test which confirms your language ability or create a piece of art that captures the experience.
Whatever you do, DO NOT expect your experiences to speak for themselves. You must market yourself and your experiences. You must tell people what to conclude from the data you provide on a resume or cover letter. A vocation helps to capture your experience and interests and demonstrates that you are pragmatic. You understand the demands of the real world and you are taking steps to become employable and effective.