Practice, essentially. Hypnosis is a skill and so is being hypnotized. Obviously as a married couple there's a pretty deep level of trust there already but getting used to dropping into trance is something to practice.

'Fractionation' is an impressive-sounding term you can search for on Google but basically means putting someone into trance, establishing a feeling of warm-safe-happy* associated with trance, bringing them out, then quickly (often before they fully wake up) dropping them back again, rinse and repeat. It's one of the best ways to establish and reinforce a 'trance now' trigger and increase depth of trance, and to give you confidence at 'improvising' induction

Beyond that...discuss.

*plus, you know, stuff like 'pleasantly aroused' or 'submissive' not likely to feature in the average hypnosis script.