Collaborators are often your supervisor’s collaborators, or people within their sphere of contacts.  You should be prepared to look at other collaborators beyond that group if you feel they have something specific to offer, e.g. if you think that spending some time with their group would enhance your Fellowship.  So scope them out as you did your supervisor, electronically at first and then ideally either by telephone or in person.

A Confidential Disclosure Agreement should be in place if you are sharing anything that you might wish to remain confidential, or where the employer (usually University) are developing Intellectual Property (IP) – even if it is only preparatory work.

You may need to consider the need for a Materials Transfer Agreement.  Your IP department, R&D department or university legal team can advise on this.  This can be time consuming, so plan ahead!