Different methods :
1- a book + CD-ROM/MP3 (ex : Assimil) and a grammar book. Try to spend at least 30' per lesson
2- reading newspapers and start with small pieces and a good dictionary and write the new words in a notebook that you can bring along with you everywhere
3- watch TV/movies/TV shows with subtitles in the target language on so that you learn and visualize better new words and expressions
4- listen to the radio and talk to friends.
On every big step, book a lesson with a teacher just to get on track and be sure not to lose any motivation! ;)
Keeping yourself motivated is always challenging and that is surelykey number 1 to reach your learning goals.