Being appointed as a trustee is a great honor and great responsibility. If you have been appointed as a trustee for someone's estate, this means that you have been chosen presumably because you have been deemed both capable of the various responsibilities entailed in being a trustee and also trustworthy to carry them out. Being a trustee is not only about handling a grantor's affairs when he or she passes or become incapacitated, it is also about handling his or her assets while he or she is still living. If you are feeling unsure or overwhelmed by this new role, don't worry — you don't have to do it alone.
Ideally, the grantor of the trust (the one who is establishing it and who has chosen you as a trustee) will familiarize you with the trust. This should include all the relevant documents, assets and monetary instruments, although the grantor may not want to give you specific information about the value of various assets. This is fine, provided that you have enough information to execute your duties. You will also want to know if there are any other trustees, how to contact them and what their specific roles are. If you are at all unsure of how to do this, the assistance of an experienced trust and estate attorney can help make sure that you are set up for success.
As a trustee, your responsibilities should be spelled out clearly in the trust document, and you will be bound to act according to the specifications of the trust. Trustees are entrusted with the assets of others because they are deemed trustworthy. You must be very careful to not mix up your own assets with the trust's assets. The trust should indicate how you are expected to treat the assets and the beneficiaries of the trust, but, in general, you must treat all beneficiaries equally, and not use the assets in the trust for your own gain (unless the trust document allows these kinds of things).
Finally, you must keep excellent records of how the assets held within the trust are handled. This will help ensure that you are free from any suspicion of mishandling your duties, and will allow for easier accounting, especially during tax time.
Source: estateplanning.com, "Understanding The Duties and Responsibilities of a Trustee," accessed Sep. 08, 2016