How can i use a fuse correctly and safely?

Hey guys, i am a university student in electronics, but i know little about it, i mean, when it comes to applying the knowledge into real life, i get lost, like if i got to one of my friends' home to catch a party, but it chanced that it "blacked out" ,while "fuse question" it turned out, there seems nothing that i can do.
So,to use fuses like this one "http://www.kynix.com/uploadfiles/pdf86758/0001.1001.PT.pdf" (not this one especially)correctly and safely, what are the "Do's" and "Don't's" ?
Or am i wrong in thinking that it is us who should repair it? Should we always rely on the "techniques" to fix it?
Thanks you guys coz my friends and i met this for several times,any advice could be helpful. ;-)