Beginnings are much easier. So much possibility, so much yet to still to discover (I don't plan) and I used to have problems with endings until I realized just what an ending is: the answer to the beginning. It's either a yes or no if you want the fiction to have closure, and maybe if you want to leave it open.
Example:
Story begins with a man discovering his wife dead on the floor of their apartment. Police arrive, blame man. He's taken to prison and vows to find the killer.
So the beginning asks a question: will the man discover the killer of his wife? The ending is yes, no or maybe depending on what effect you're going for.