An immigration officer usually never meets you before deciding your application. They meet your paperwork. That's why experienced filers follow a simple rule: for every important fact you state, ask “what shows this is true?” — and put that thing in the package.
The three layers of evidence
Identity and civil documents: passport, birth certificate, marriage certificate, I-94. These prove who you are and the relationships you claim. Official, dated, and issued by someone other than you.
Documents that already exist about your situation: leases, bank statements, school letters, medical records, police reports, membership cards, photos with dates, message histories. You don't create these for the application — you collect them, which is exactly why they're convincing.
Statements: your own written statement, and letters from people who know the facts firsthand — a relative, an employer, a doctor. A good support letter says who the writer is, how they know you, and what they personally saw, with dates.
Practical rules that save applications
Documents in another language need a full English translation with a signed translator's certificate. Send copies, never originals, unless the instructions specifically demand originals. Keep a complete copy of everything you mail. And organize the package in the order your evidence list says — an officer who can find things is an officer reading your story the way you told it.
Pro Se builds your evidence checklist from your own interview, so every item on it ties to something you actually said. General information, not legal advice; Pro Se by Law Aid Management LLC is not a law firm.