One way to deal with demons and such is to show them that you are the biggest and meanest of them all. Of course that path is the fastest path to darkness... It works, but I do not recommend it. 
The most difficult thing I know is to fight demons without becoming one myself. That is some real jedi/sith stuff. :D

They feed on each other and they feed on you. You can feed on them or you can just leave the banquet. 

One way to deal with them is to not use your own energy to try and banish them, but connect to the "universal light" or "god" or "love" or what ever you want to call it and let them feed on that. That is too much for them to handle. But finding love can be a tricky journey in itself too ;)

Good luck what ever you choose to do!