Bring the job offer, a description of the reporting structure, and a written account of each current or planned deliverable and how it connects to the employer. Add education and portfolio background if the profession match depends on demonstrated qualifications.
Show the whole working relationship, not one project
A single project brief does not show the reviewer how the role is structured. Provide the broader arrangement: who the employer is, how work gets assigned, and how compensation is set, whether salaried or otherwise. If prior contracts or invoices exist that resemble freelance billing, disclose them rather than leaving the reviewer to discover a pattern that contradicts the employment claim.
Bring the material in the order a reviewer will want it: proof of citizenship, then the employer letter, then the credential, then the engagement description. A passport rather than a permanent resident card is the document that matters for the citizenship point, since TN is available to Canadian and Mexican citizens. Ask the employer to name a supervisor and a worksite, and to confirm that the position is temporary with an anticipated end.
Where invoices exist from earlier freelance work for the same client, bring them and be ready to explain the change in relationship, because concealing a pattern a reviewer can find is worse than explaining a genuine shift. Keep a copy of everything presented, stored where it can be retrieved quickly.