Applying for a placement is not very different from applying for a job. The aim of both is to get the employer interested in meeting you for an interview. In an application letter for a placement, you should describe your degree programme. Your knowledge is your main wager. For a good description of your degree programme and courses, programme websites usually offer clear and concise information. In a CV for a placement, you can describe the courses you have taken and include titles and summaries of papers you have written. As described in Internship Guide: Work Placements Step by Step, most applications for placements are so-called ‘unsolicited applications’.
For applications abroad, we advise you to consult ‘Looking for work in …’ by Expertise in Labour Mobility (see also ‘Interviews’).