On the first visit, the therapist will start by taking a case history; asking a lot of questions about your medical history, the current state of your body and mind, and your lifestyle. This may take some time and she/he will make a lot of notes for your records. This information will help her/him to decide on the method(s) of treatment, and oils to use.
Treatment is likely to involve a massage to one part - or even the whole - of the body, but could involve any number of ways of applying essential oils e.g. compresses.
You may be given oils to take away and use at home, for example in the bath.
The length of a session varies from one aromatherapist to another and depends on the treatment, and the first will normally be longer for the case history. In general perhaps one and a half hours for the first visit and one hour subsequently.
Prices vary from place to place, and will also depend on the treatment given, but the average in Britain is from £20 to £40. Some practitioners charge extra for the longer first session. Oils to take home will usually be included in the price of the treatment, unless a particularly expensive blend is called for.