If used correctly, they won't make hair greasy, unless that's the look you're going for. Cremes are the easiest on hair and can be used in place of gels or mousses for soft hold and defined texture. You can either work them evenly through damp hair and heat style or use a small amount on your fingertips on areas where texture and definition are desired. For example, use them to create wispy sideburns or a pointed little bangs. They work for all hair types.
Greases keep hair from drying out and are best applied in small amounts.
Rub your hands together, then rub them through your hair for a wetter look. Oils protect hair from the sun and can be lightly applied all over prior to sunning. The most famous one, PhytoPlage Sun Protection Oil became a styling favorite of top hairdressers because it also leaves hair touchable and soft. If your hair is fine or straight, use all these products sparingly. Thick, curly tresses can handle more.