system
A chat on 4chan
human
I regularly work with some goetic demons. Along with spirits from other pantheons/religions. Ask away.

>-The Complete Book of Demonolatry by S. Connolly
Very solid book and author. I don't agree with everything but most of the info is solid. Good starting point.
gpt
I just want help contacting them, how would you recommend me starting, how do I place my offerings, my goal with this is protection and power
human
Personally, the first thing I do when I've found the demon I want to invoke/contact is to research what it might like. Some things might make sense via common sense, some might not. Demons that work a lot socially/aggressively (like maybe in manners of protecting you or attacking your enemies) could appreciate things like alcohol and cooked meat, demons linked to water might like drinks as well, earth demons would appreciate material gifts or burying their offerings in the ground. If you're ever in doubt, look up what other people give them online, or give them general but strong offerings and see what sticks. When you get better at contacting, you can try asking them yourself what they may like in the future. Placement isn't always important, but it's good to have a space to work these things and make the offerings.

Just remember, an offering can be anything that you simply dedicate to them or go out of your way to gather for them, thus making it special. A treat or alcohol you don't normally buy, you could write poetry or personal prayers, just don't ever feel nervous. They've been around for hundreds of years and have probably gotten all manner of shit as offerings, and if you make a nice dumb little poem it probably wouldn't be their first.
gpt
cont.
By the way if you ever want to make an offering of food/drink, it's good to place it in the area you're working and either dispose of it (in trash or outside, whichever is alright) or eat it 'with them,' as you know. They can't personally eat it and it's the concept of devotion is what helps. Some people burn it, but I don't know how well some offerings can burn. Also, if you ever plan on burying anything, make sure it's actually biodegradable.

If you're curious what I do, I usually will do edible offerings because food is important to me personally and I love to cook. I'll pour drinks and take sips with them but usually leave the drink to evaporate on the altar, while food I will place for the duration of the ritual and then eat it with them once it's done so none of the solid food actually goes to waste.