What is the best way to get a good score on the sat?

Its my junior year and im going to taking my first sat this year whats the best way to prepare and how long should i study to get a good score? is it hard? What are some good test taking skills if im kinda a slow tester? how long do you have to take the sat? Is it better to guess or not awnser questions you dont know? PLEASE HELP !!!!!!!