But there are some rules though, eg all words ending in -eit (so -heit, -keit etc) -ung are always feminine and die. All alcoholic drinks are "der" except bier which is "das", most wordings ending in "e" are die but there are exceptions such as der Name, das Käse

The above I learned a while ago when learning German but otherwise it just seems to be something you get used to and stop worrying about after a while and the gender seems to become natural, almost instinctive. I have no idea how it gets decided what a new object will be. For example, how did they decide upon the gender of a DVD Player?