Marbas or Barbas is described as a physician, architect, and mechanic by many sources. The mechanic is the most interesting analogy. From first hand experience when you pay to have something fixed, most of the money goes to labor. If you collect the parts and put it together on your own, you get more out of it in the long run.
For beginners, it will be temping to call on a particular spirit to help with a particular problem. This is wasted effort. Many descriptions in the goetia contain the phrase “He teaches men the art of…”. When you work with a spirit, you are their apprentice. When you ask to have a woman fall in love with you, ask “what is the process? What inside her are you changing? How do I do this?”
I planned to summon Marbas to heal a wound. But then I thought more long term. I don’t need him to heal me. I need him to teach me Reiki and medicine. Don’t ask to be healed. Ask for a scalpel. Don’t ask for a spirit to be exorcised. Ask for a sword. Don’t ask for protection. Ask for a shield. Along the way, you’ll have a collection of tools the lead the way to your own self-sufficiency. Any ritual or chant you channel form a spirit is consecrated with their power. Their’s no need to fully evoke them.
This is just something to think about if you’re working on getting your life together like I am.