Referrals - How to decide?

Hi all, I have recently joined a new company and a lot of people (mostly people I don't know) are reaching out for referrals. I know the time is tough. How do you all decide whom to refer? Friends and people you know are definitely there. You can't be referring everyone as it decreases your credibility if they are not suitable for the role or don't get hired. Also, how do you say no to such requests? Thank you!