Angels communicate with humans in many ways. They may appear directly to the individual to bring a specific message. In biblical times the angels communicated with the prophets through visions. One of the most important ways that angels communicate is through intuition. Many associate this voice with that of their guarding angel.
Angels also superimpose themselves on individuals in order to bring a message.
To keep anonymous, angels will manipulate circumstances to give help to an individual. These circumstances appear to be coincidences, such as the meeting of two strangers. One stranger may be in need of assistance, the other is able to give the needed aid. They may even use a situation as simple as a book's falling open to the exact page that gives a much needed answer to a problem. Whatever the message, whatever the need, the angels communicate help in variety of ways.