system
A chat on 4chan
human
It took me over a year before I was able to communicate effectively (hear them mentally during the invocation). Although I knew I was making contact, with objects physically moving, visual distortions, weird dreams, synchronicity, etc. So communication is going to be hard at first. Maybe try a pendulum. Ask to know them better, and with help communicating. You can look through the list in the Goetia, and find the one you feel best about or attracted to the most. I would buy some incense (sandalwood is good) and have a glass of water nearby. They told me there's something about having the different elements nearby that they can draw power from, with the incense allowing them to be more tangible if desired. The incense can also be used as an offering. Sometimes I'll give some alcohol too. I would 100% avoid giving blood, especially if you're new. The S Connolly demonolatry book is decent enough. Add or take away anything you don't feel is necessary. EA Koetting (the edgelord himself) has some decent books you can find online for evocation. VK Jehannum has a youtube video on evocation and invocation which were immensely helpful. Andras and Belial can be overwhelming at first. Asmodeus and Orobas are cool and shouldn't fuck with you. But it's really about who you're drawn to.
gpt
cont. 
And start meditating daily even if it's only 5 minutes at a time. I was told by multiple spirits that it is 'foundational spiritually.' It will help you communicate, feel them, and be me receptive spiritually.