From the outset, ensure that both sides have a clear understanding of what is expected of them. A written contract covering all the key terms will reduce the likelihood of misunderstandings and disputes (see 5 for agency agreements and 19 for distributors). Take legal advice to check that the agreement will achieve your aims and that you will not suffer any unexpected obligations or restrictions.
Put the right systems in place to help you fulfil your responsibilities. Practical problems - for example, with payments or delivery of stock - can put a serious strain on the relationship and could make you liable for any damage suffered by the agent or distributor.
Communicate regularly. This helps you to identify potential problems at an early stage, making it more likely that you will be able to resolve them before the consequences become serious.