How can I recognize if a person is good subject for hypnosis? Which behavior/personality traits should I look for?
Despite quite of lot of research looking for personality correlates of hypnotisability no very clear links have been found. There is evidence of weak associations between hypnotisability and absorption (the capacity to direct a great deal of attention to a narrow range of stimuli, such as getting caught up in film or book) and also of associations between hypnotisability and fantasy-proneness (the tendency to engage in imaginative activity) - but neither of these characteristics has much practical predictive value. 

Instead, in scientific hypnosis, rather than using indirect personality measure to identify hypnotisable participants, researchers use measures specifically designed to measure hypnotisability. The most common measures are the Harvard Group Scale of Hypnotisability and the Stanford Hypnotic Susceptibility Scale. Both of these are behavioural measures that consist of an induction followed series of simple hypnotic suggestions (e.g., your arm will heavy). Following the suggestions participants are scored as passing or failing each suggestion based on whether they meet a specific criteria (i.e., did they drop their arm more than 6 inches). The more items they pass, the higher their hypnotisability.

So in summary: personality cannot reliably predict hypnotisability. To tell if someone is susceptible, the best way is to see how they respond to hypnotic items.