Dear Waterrat,
Language-wise, English uses an alphabet, which is based on its phonological system. Any time you read or write, you are subconsciously improving your listening and speaking skills. The only catch as a foreign language learner is that you have to correlate the phonological and orthographic systems.
Motivation-wise, it really depends on which culture you are coming from and which teaching methodologies you are accustomed to and expect from the teacher figure. For example, if you are studying to improve your composition ability for the IELTS, then focus on reading and writing. On the other hand, if you are getting ready to travel abroad on a business trip, a focus on conversational business English should be exactly what you are looking for in addition to cross-cultural knowledge of how to conduct negotiations in the culture you are traveling to.
For more information, find me on-line.
Sincerely,
Eric Paul Monroe
http://www.eric-tesol.com/