Moisturising curly hair is important mainly due to the fact that our natural oil (sebum) secreted from the scalp does not usually get from the roots the tips of the hair efficiently. This is because of the many bends and spirals in the hair and thus, the oil must go through a larger surface area. Usually with curly hair, the roots are well lubricated but the ends of the hair remain dry and as a result, this causes many of us to invest in moisturisers and oils to seal the ends.
Hair that is moisturised will exude natural lustre an shine/sheen and will be soft to the touch, however, hair that is dry will be rough and look dull. It does not take much to moisturise curly hair; all it requires is that you remove product build-up that potentially prevents moisture from penetrating the hair shaft. The next step would be having a good moisturiser that will hydrate and nourish the hair and this must be sealed in by an essential oil or natural oil: Coconut oil or Castor oil for example. Finally, consistency is what will ensure your hair always looks good.
Side note: beware that the feel or touch of the hair is sometimes not enough to conclude that your hair is dry as some gels and holding creams leave a cast on the hair, giving it a hard feel. In this instance, simply running a light-weight oil through your hair will get rid of the gel cast.