How do you act like a guest at others house?

Well, as a guest you don't live there. So, if you want to do anything except visit, you ask first. If the opportunity presents itself to help with clean up after a dinner or to run a quick errand, it is nice to offer. Emptying the dishwasher is a nice thing to do, if the hostess doesn't mind. Avoid snooping, even if the medicine cabinet begs for a look. Leave the toilet seat as you found it, or put it down. If you are there for an extended visit, pick up after yourself and keep your belongings at or near your suitcase, rather than leaving them in different rooms in the house.