tarot cards and crystal balls

Does a medium or psychic reader need tools such as tarot cards or crystal balls? No - not really. Sometimes when reading for a client it's useful to have a fallback. Some clients are more difficult to read than others. If a person is particularly negative or closed minded their energy is dense and the aura sits close to their physical body, this makes it harder for the medium or psychic to penetrate and to make a link to the client's chakra system, which is where information is stored and energy connections made.
In such cases when the medium/psychic is fighting for information instead of it flowing naturally a prop can be a useful distraction for the client to focus upon and therefore alleviating their fears of the process of being read. Also a prop gives the medium/psychic a positive point of focus and leads to the flow of energy and information rather than a mental block which causes the information to cease.
When reading for someone and the medium/psychic has some information that they decide not to pass on to the client because for example it seems harsh or the medium/psychic is uncomfortable with the subject given, the flow of information will pause. Until the statement is made to the client little or no further detail will be given and it becomes a block. The medium/psychic is not the person who can decide what information can be passed to the client, they are an intermediary only, a voice for those with no voice box or a conduit through which information is passed. Using the thought process interferes with the benign condition that the medium/psychic needs to adopt. They should not have an opinion or judge you in any way if a successful reading is to be achieved.
A spirit medium who has a good connection with the spirit world does not need to use props at all but there are times when it helps the client to relax and to calm their nerves during the sitting. Cards and crystal balls and similar tools allow the reader to tune in to psychic energy, a good medium will know the difference between psychic energy or if they are in connection with a spirit person.
The client can tell the difference in the following way; a message from spirit will include a description of the spirit person. It will not necessarily be a physical description of how they looked on earth and how you would recognise them, it can instead be a description of their character and their behaviour and opinions whilst you knew them. That depends on whether the medium is clairvoyant or clairsentient. Some mediums are both but not all mediums can do both, some never see a spirit person and always sense them and the reverse is also true.
Also a message from a spirit person will include evidential details of their existence and will contain memories that you can identify with. It will also contain advice for the future and regarding a current situation. You are able to ask a question of the medium and spirit usually answer in a way you can understand.
When psychic information is being drawn by the psychic the above descriptions are missing, instead you will receive information about a current situation, health issues, and more random details that are not always connected. A psychic reading doesn't hang together the same as a mediumship reading because of the way information is gathered by the psychic from the clients aura.
More usually during a reading there is a mixture of the two techniques which leads to a more rounded and useful reading.
Ultimately it is the mediums job to give reassurance and solid advice to the client, any medium who claims to solve your problems, heal your life or illnesses is breaking UK law. A medium that delivers a string of bad news is not working properly either. Spirit who live in the light do not often give a passing, especially if it will cause distress. It is true that they may give it but it is usually to someone of deeper understanding or if softening the blow is the best thing to do. A medium may pick it up psychically but a reading is supposed to be a positive event. If you have a reading with someone and you come out of it drained, despondent and worried for the future then don't see that medium again, find someone who is registered with the SNU or a registered psychical society where they receive training and guidance and development throughout.
However, don't blame the medium/psychic if they get everything wrong about you and fail to read you. Sometimes this happens to the best mediums. It may be that you are not supposed to have the information. Some of you are here on earth to be a grounding agent, be pragmatic and practical during your life time. You will be connected to earthly and material issues and it's not necessary for you to have esoteric input for a good reason that you may or may not be aware of. Accept it for what it is - not for you. Personally, on the rare occasions that this has happened to me during a sitting, I don't charge a fee. Some mediums do but I am not happy about taking something for nothing. That's not to say that I take responsibility for not being able to retrieve any information for the client, I merely accept that it's not meant to be. If you are going to visit a medium or psychic make sure you go with an open mind, just see what comes and what happens, that's all the medium needs in order to connect with spirit and it makes their job much easier, do not expect or wish for certain things to happen during the reading or for certain people to come through, you may be disappointed, instead trust that what you need and is for your highest good will come.