Make different kinds of presentations to different kinds of audiences, including factual and persuasive presentations and, if possible, one to an audience hostile to your case. Make the most of opportunities to travel. Learn a language. Take an interest in the local culture, even the economy or politics. This could be through vacation work, intercalculated or time out work, sponsorship, or by choosing a course with a placement or employer related project.
Any work experience is useful.
Working with members of the public is especially valuable. Small business experience is productive. You may be given more responsibility, and there may be a wider variety of jobs to be done. Spend occasional days work shadowing family and friends at work. This will help you explore many more options.