I've worked with Hermes so much that sometimes I can just plug into the Mercurean current.
For deeper or more specific connections to Hermes: the psychopomp and the messenger, I have several strategies. First, I have tied the scent of lemongrass to this archetype, so I will have some lemongrass oil diffusing while I read stories involving Hermes. The hypnogogic state, just between waking and sleep, and the hypnopompic state, just between sleep and waking, are great times to get in touch with Hermes. (I might even smell lemongrass during the hypnopompic state if I'm making the connection.)
Another way to plug into Hermes is to plug into my Jungian Animus., with particular care to plug into the spiritual guide aspect of the Animus.
Hermes is also associated with the color orange and oral traditions. I'll read over any relevant lore during my prep time specific to the reason behind my wanting to connect to Hermes.
If I'm having difficulty making the connection, I might design a ritual and wait for a couple of days to see what happens.
Sometimes, if I want to get to a specific part of my unconscious mind, a totally different guide might guide me there instead of the one intended.