There are 5 "suggested spreads" that accompany the Tarot of the Inner Mask Oracle, but there's another method of using these cards that I think works brilliantly with this deck: "Three Themes of Your Life."
Lay out 3 cards in a row from the Inner Mask Oracle. You might've seen people do 3-card readings with Tarot, often calling these past/present/future. I have never found this to be quite fitting for the Tarot of the Inner Mask, which wants us to go inward always.
Three themes of your life has no chronological order, nor necessarily order of emphasis. If you see relationships between the cards that's relevant based on their positions, then by all means I encourage you to follow that line of inquiry, however it is not necessarily always going to be there. Three themes of your life are the active principles alive in your world at the moment, the messages the universe is sending you, the types of change active in the present chapter, the forces acting on you in concert most powerfully now. You select 3 cards from the Tarot of the Inner Mask deck, and you look at what that card is saying to you, where in the course of events in Maskworld the depicted character is shown, its relationships with things around and inside, its feelings, its confusions.
The Inner Mask is a creature who is often overwhelmed and confused by things around itself, but there is quite often a source of enlightenment nearby, a reason for the complexity, a sense of order somewhere. When we turn to the Inner Mask Oracle, we are asking to make sense of things, to listen to what the Shadow has to say, to learn how to cooperate more closely with different layers of our own selves. We are difficult machines in a way, complex and without a manual. We resolve our complexity by looking inwards, and also by looking outwards.