Where do I start when re-furbishing my shed?

I want to clean up my shed so I can use it. Theres cob webs every where and the paint has peeled. Theres three glass windows that have smashed and theres bugs everywhere. Its filled with all this junk that I want to get rid of and I know how to do that but I dont know where to start after. I am going to put some old pc's and televisions in there so I want atleast some decent security. I dont want a filthy shed I want it to be clean like a house would be.