What information did you give to your domain registrar?

I'm looking forward to purchasing a domain from namecheap for the first time. But worried about providing the information they're asking for. Should I fake it? or provide real details but in a little vague manner, like only giving my first letter of my surname? same with the address and other details(except phone number)

Just wanted to know how you guys did it and suggest me some tips as well.

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