The following are good resources for approaching philosophy in general and/or for narrowing down your search to specific branches or fields of philosophy.
The Internet Encyclopedia of Philosophy (IEP) (ISSN 2161-0002) was founded in 1995 to provide open access to detailed, scholarly, peer-reviewed information on key topics and philosophers in all areas of philosophy.
The Stanford Encyclopedia of Philosophy organizes scholars from around the world in philosophy and related disciplines to create and maintain an up-to-date reference work.
Founded in 1999 by college educators, the Sophia Project is an online collection of original articles, primary source texts, and commentaries in the fields of philosophy and ethics designed to provide the newcomer to the discipline of philosophy with the resources necessary to read great philosophical works.
PhilPapers is a comprehensive index and bibliography of philosophy maintained by the community of philosophers.
The Routledge Encyclopedia of Philosophy Online (REP Online) is the largest and most comprehensive resource available for all those involved in the study of philosophy.