Precede the meeting with a letter setting out the agenda, and keep the discussions simple. Follow the meeting with a letter summarising the main points, and the agreements and actions reached. Try to be helpful. The two biggest mistakes deputations to government make are asking for too much, and raising problems without offering solutions. Rehearse what you are going to say.
Ministers like to help but they are driven by many conflicting pressures.
To be effective, the contact has to be on-going. You will not achieve all you want in one meeting. David Kindon, a Canberra PR consultant, carried out an illuminating survey of politicians. He asked them how they preferred to be approached by lobbyists. Working out who the best people are will require some preliminary work, and you will need to use Departmental contacts to lead you to the right people.