More than in many genres the freedom allowed in science fiction leads to the necessity of finding good authors. Without knowing who the author of a story was it is difficult to have any idea what to expect. Consider the story of a detective investigating the suspected murder of a human by a robot. Written by Philip K. Dick you have a tale of paranoia and questioning of reality, written by Isaac Asimov you have "I, Robot", and both of these are good authors. So who are the authors the most famous science fiction authors, the ones who can be relied upon to tell a good story every time?
Starting at the beginning you have Jules Verne and H.G. Wells. Their stories are sometimes a bit dated but they are almost always good stories with nearly every element of more modern science fiction in their pages at some point. With these writers you can travel to the center of the earth, the moon, through time, meet alien and more.
Throughout the early part of the century there were many good science fiction authors but the golden age of science fiction didn't start until the late 1930's. At this point man began to understand his own ability to destroy himself and the power at his hands. The world seemed on the edge of either destruction or a golden age and we didn't know which. At this time I like to go with the ABC route of authors: Asimov, Bradbury, and Clarke. This leaves out a great many excellent authors out but is a fantastic place to start.
Isaac Asimov is one of the most prolific authors in history. Asimov wrote over 400 books including "Foundation", "I, Robot" and "Nightfall", as well as a great many short stories, and numerous non-fiction works on science.
Ray Bradbury didn't limit himself purely to science fiction sometimes writing stories that were horror but he is best known for "The Martian Chronicles" and "Fahrenheit 451" two of the best known science fiction stories of all time.
Arthur C. Clarke is a British author and one of the harder writers of hard science fiction. Often sticking with stories nearer in the future he is best known for "Childhood's End" and "2001: A Space Odyssey" and many others.
There are simply too many great authors of science fiction to list them all and at some point you will learn the style of story you want to hear. Asimov often deals more with psychology than hard science, while Frank Herbert will give you every detail of the world and Robert A. Heinlein will give entertaining wish fulfillment.
There are fantastic modern authors as well but their body of works is often much smaller and still growing. In repayment for often having less work they are able to relate their stories more specifically to the world we live in now. Two of the better ones are Orson Scott Card, who wrote "Ender's Game", and Neil Stephenson who wrote "Snow Crash".
Any time you try a new author it is like meeting a new person. You may like them but do you have anything in common? Do your views meet, your ideas of fun? Yet meeting people is necessary or your world will quickly grow very small so pick up books from the most famous of science fiction authors and see which you like.