Try to have different layers of different things based on the list below. For example, the bottom layer could include damp wood, bark and moss while the top is drier and filled with straw.
Take a look at these materials and decide what you want to include:
Packing your insect hotel with sticks and twigs will attract ladybirds and lacewings.
Wood will entice bugs such as stag beetles, woodlice, spiders and centipedes.
Straw and hay attracts invertebrates such as ladybirds. They also like pine cones to lay their eggs in over winter.
Leaves will mimic a woodland floor so it attracts insects like butterflies, beetles and spiders.