If you meditate it will be much easier. The amount of time you use for scrying can vary from a few minutes to half hour. You usually scry alone but more than one perosn can scry into the same surface at the same time for information. Though some people go through rituals before they scry - it isn't necessary. If you wish to ask your spirit guides for guidance go ahead.
Some people say a little prayer and ask for the correct information to appear.
You will actually see these images with your eyes. Once this happens, images may begin to form in your mind, no longer projected onto the scrying surface. When this happens, allow your attention to focus on these mental images. As the images become clearer, you will find that you know things about what you are seeing background information will come to the surface of your mind. Pay attention to what you know about the images you are seeing.