I am always one of those people afraid to like, make myself at home at others'. Like, getting ice from the fridge or asking for more food, not being enough seating, stuff like that. Better as an adult, but I was really bad about it when I was younger. My family also never really hosted "adult" things so it's been kind of a learning process as we've started hosting things.
So I feel like I'm a super conscientious host because I'm always like, what would make me feel weird and anxious at someone else's house? Ok, make sure extra toilet paper is easily accessed. Plunger too, haha. If you want people to bring stuff, be clear about it and give them a category of what you need - dessert, appetizer. Put out ice. make sure we have extra food so 10 people aren't fighting over two pizzas (honest to God, a friend hosted something once and they served two frozen pizzas for a mixed crowd of 10, I went hungry), make sure we have enough seating........friends have commented that we throw good parties and always have too much food, haha. It is a lot of work but I've found I rather like planning and hosting. Get to stay in my own house where I know where everything is!