See to it that he doesn't have the whole house - one room is enough. Leave him with a used t-shirt of yours and his favorite toy. Every time you go out the door say "I'll be back" as the very last thing you tell him - every time - even when you take out the trash. Even though he doesn't understand the words he will understand the meaning after a while.
Do not "feel sorry" for him when you come home and show him that - be happy when you greet him
And don't ever put him in a crate - being alone is not a punishment and he will feel that if you crate him.
Good luck