How does a firewall work? I am no expert but there are a couple of pointers. Firstly the computer firewall will block everything from anyone it has been told to block. You and I should do likewise. If you have had a bad experience of any particular source, be it a person or an organisation then blank it out. Ignore it in future. Don't go near it or them. Pay no attention.
Another approach computer firewalls use is to only allow into the computer information that has been requested by the user. Good plan for life. Pay no heed to folks offering you info you did not ask for! This cuts down dramatically the daily load. You can safely ignore all advertising, junk mail, fliers etc you encounter on the streets, in the media or on the Internet. Any approaches from commercial organisations, politicians, religionists or senders of spam you can blank out and your life will be richer and calmer as a result. If however you approach any of these groups or individuals seeking information or advice all well and good.
Remember this - most unasked for approaches make promises to you. Most promises will not be fulfilled. Expecting such is to be disappointed. How much disappointment can we handle? There is a limit. As said before -trust yourself, your family and your friends. You know them well, you know how to work with them, you can adjust to their individual personalities. But mostly think calmly and trust yourself