Set up many approvers

Actually, everytime a request is created by other users a new request is created automatically and assigned to me (I am the approver).
I would like to setup another approver for my own requests. If I create a request, I want it to be approved by someone else.
So to summarize:
1- All users requests should be approved by me
2- My own requests should be approved by another user

How can I configure this behavior?

Thanks for your help