The gents over at Bolter & Chainsword produced an outstanding guide to using Space Marines in Warhammer 40,000 5th Edition. It is a well produced 74-page pdf. It focuses on what is new with the 5th edition and what has changed. It covers all aspects of play and even has sections on specific Chapters such as the Dark Angels.
Use this along with the 5th Edition Preview/Review and you will be all ready for battle when 5th Edition arrives.