You can practice most things alone, but to really practice speaking you need a partner. And you can find native speakers to practice with at SharedTalk, LiveMocha or Conversation Exchange (REMEMBER: Always protect your privacy online). These sites will all help you find someone who speaks English and wants to learn your native language so you can practice in tandem. You might speak 20 minutes in English and 20 minutes in your mother tongue....

English Club has lots of information, quizzes and guides to help you understand and practice English better.  Their forums are a great place to chat with other learners about things that interest you.