Collect identity and family information, the precise proposal under consideration, and specific questions about eligibility, funding and the current instructions. Follow the official directions for any subsequent USCIS forms and supporting evidence.
Work from a dated, official reference
The official website explains that applicants receive further USCIS instructions after the initial payment step. Review those requirements before assuming a file prepared for another investor route can simply be reused. Keep a record of which version of the instructions informed the plan, since a generic checklist should correspond to the actual current process rather than replace it.
Keep a dated record of the official terms in force when the decision is made, together with the civil, identity, immigration-history, and source-of-payment documents that support later vetting. The first review should identify who can obtain any missing record. Hypothetical example: a Québec owner of a specialty-glass studio plans to pay from the sale of a warehouse.
The useful file includes the ownership record, sale agreement, closing statement, bank deposit, and payment trail, not merely a screen capture of the sale. Preserve the official instructions separately, because a payment route is not a substitute for documentary screening.