General
Artist and art institution should consider together the possibility of external funding.
In contract discussions, make clear starting agreements and appoint formal moments to adjust the agreements as needed during the process. Formalize the agreements in writing, based in part on the model contract.
Make clear agreements in advance whether the work fits into the category of "new work," "adaptation of existing work," or "existing work.
Production budget and expenses are not included in the fee. Make additional arrangements for these based on a project budget or quote. Consider: production and material costs, hourly budget, the process of calculating and accounting for labor hours to be charged, payment of travel expenses, other expenses and per diem.
Agree in advance on duty of care, liability and insurance.
As an artist, are you affiliated with Pictoright to manage your individual copyright? If not, consider doing so; it saves a lot of tracking, phone calls and negotiations. As an artist, you are then assured that your work will only be published with your permission and for a reasonable fee based on collective management agreements.
Agree on payment terms and VAT rates.