Start with the W's.
Take note of the "what", "where", and "when" of the meeting. Start with the reason for the invitation. It can be a social or a business meeting, a meeting outside the office, a meeting about your sales report �" basically, it should start with what your email invitation is all about. Include where and when the meeting will be held. If you have the details of the duration of the meeting, include those as well, so that the recipient can schedule other appointments before or after. Mention if any food or refreshments will be served at the meeting.