The various deepeners used below are useful for helping someone reach a 'lower' level of trance. Of course, all of this talk of 'deeper' and 'lower' is simply metaphorical, but it serves a helpful purpose.
A popular - and effective - deepener is the simple Staircase. This involves inviting the client to imagine walking down a staircase, becomming more relaxed with each step. It's a simple way for them to focus on the process of becoming increasingly more relaxed, whilst employing their imagination to reinforce the point. Most of the deepeners listed below are variations on this theme.