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.
Instead of looking for personality traits, we can conduct some explicit visualization tests:
make two fists, bring hands together making thumbs and knuckles touching itselves, extend index fingers, pick any spot and focus attention on it, breathe and exhale slowly and deeply three times and close eyes, imagine that tips of fingers are magnetized and are being drawn closer and closer together and magnetic attraction is growing stronger and stronger until soon they actually touch
extend both of the arms straight out that the palms of hands are facing each other and thumbs pointing to the ceiling, turn left hand palm to the ceiling, take spot at thumb on right hand, breathe and exhale slowly and deeply three times and close eyes, imagine that there is a thick, heavy book in the palm of left hand causing the hand to feel heavier and heavier, being pushed all the way down; imagine a string tied around right wrist, string connected to giant balloon filled with helium gas gently drawing arm higher and higher into the air so soon arm will be pointing straight up into the air
Hypnotists always look for vesiculated motion - not a smooth motion, but tugged and jerked one.
Anthony Galie - https://youtu.be/I2EhK9itRME?t=12m47s
David Lion - https://www.facebook.com/lionismtv/videos/1182427528493167/