There are quite a few mistakes executors make. I recommend talking to an attorney. As an executor your responsibility is to collect all of the assets of the estate and then manage those assets. An executor is also in charge of making sure that all the creditors are paid.
There is a certain priority order of how creditors should be paid. The most common mistake as executor can make is getting all the assets together and then paying off credit cards, utilities bills, notes, etc. without knowing the order in which everything should be paid. Without talking to a qualified estate planning attorney, an executor runs the risk of being held liable for not paying or not taking care of certain aspects of their duty as executor of the estate.