There are three basic types of cassette tapes available. Your choice of which cassette to use should depend on how important quality and clarity are to your recording. They work best when recording non hi-fi recording for portables, like a lecture or interview. These tapes are reasonably priced and are good for recording most music applications. These are high bias tapes.
Metal tape is more expensive but is the tape of choice for the highest fidelity recordings.
There are also high bias tapes, and are particularly good when used over and over. Cheaper or lesser quality audio cassette tapes tend to not hold up with re-recording audio. The various functions of a cassette deck vary widely on which brand and what type of deck you purchase, but here are some of the basics that you may feel are necessary when buying your deck. Whether you have a single or dual deck cassette player, an Auto-Reverse function proves very practical. This applies only to dual-cassette decks.