Purchase tapes that fit your specific needs. For example, if you want to learn Spanish so that you can travel to Spain, you'll want one that focuses on the Spanish dialect, not Mexican Spanish. You'll also want tapes that teach the Spanish you'll need as you travel, such as asking for directions and ordering at a restaurant. If you want to learn Spanish so that you can speak with your grandmother who doesn't speak English well, you'll need to know different types of phrases.
Play the tapes as often as possible. If you have a tape player in your car, that can be the perfect time to study, but you can also listen to the tapes while you work out, at home or on your lunch break. The more often you listen to it, the faster you'll learn Spanish.
Repeat the key phrases. As you listen to the Spanish tapes, there will be a pause after the speaker to allow you to repeat the phrase. Speaking out loud is the key to learning to speak Spanish naturally. You may feel a bit embarrassed about talking out loud at first, but it's the best way to improve.
Proceed through the course at your own pace. You can repeat the tapes until you feel that you understand the phrases on that tape. Then, move on to the next tape. Feel free to go back to review a tape that you already studied.
Supplement your studies with Spanish music tapes. Once you are feeling more confident in your Spanish abilities, you can listen to Spanish music and try to understand what they are singing.