Ms.ROCHELLETOBIAS, the invitation letter is not required for tourist visa application. Please don't worry. For Greece citizens, the following documnents are required:
1. Applicant's passport with blank pages and at least 6 months validity left before expiration.
2. A truly and completely filled application form affixed with one passport-size or 2x2 colored photo, with white background, full-face front view, and no hat. Photo must be glued on the application form. Stapled pictures will not be accepted. Scanned photos will also not be accepted.
3. A copy of the round-trip plane ticket
4. Hotel Reservation