It would be better to say, "How can I improve my listening skills?'
Retaining your original structure:
How can I be excellent AT listening? That works, but not as well. Most people would want you to change it to "How can I become excellent at listening?" or something like that.
Well,
you could listen to something with a script in front of you, so that you could read the words at the same time
you could practise and practise and practise
you could engage conversation with a language exchange partner
you could hire an English teacher who will talk clearly at your speed, and repeat things that you don't understand
That's all that comes to me at present.