Summoning demons can sometimes feel like a chore, but there are various creative ways to get dark lords to appear before you. For spiritual people, the best recommendation is to meditate on their enn and combine it with a binaural frequency attached to them. Playing it in the background for a long time helps you to connect with that energy as well. You can also compliment them with sulfur vibrations since sulfur is associated with hell and has its own spiritual properties.
Besides the obvious methods like giving offerings of water or liquor on your shrine when appropriate, drawing sigils on your body with eyeliner is a good way to create a direct connection to them. Even just a pentagram or alchemical sigil can help you connect since it enhances your energy.
It isn’t actually that difficult to make them appear, but many of us do not have the tools or the senses to pick up on their energy. Talk to them, offer them gifts, and ask them what offerings they appreciate to see if you begin physically hearing what they have to say. It is more common to have their knowledge downloaded into your mind, but this can be tricky for beginners who do not yet realize how this happens or how to differentiate it from their own ideas.