A clear file is easier to approve than a large file.
Identity
Keep passports, civil documents and any required certified copies current. Names and dates should match across the file.
Address
Banks and authorities often ask for recent proof of address. Make sure the address is written consistently and the document is recent enough for the institution using it.
Source of funds
Be ready to show where the money for a transaction came from. Salary, dividends, a property sale, investment proceeds or a business exit should be supported by documents that connect clearly.
Company documents
For business banking, expect questions about ownership, activity, clients, suppliers, expected turnover and payment countries.
Takeaway
The reviewer should not have to guess how your story fits together.