The best way to get good hairstyles is to find photos of the hairstyles that you like. Alot of the hair and clothing are inspired by real life clothing and hair. The hair clumps are just hairs clumped together. A good way to see this is like spiky hair in cosplay or people with spiked hairs. It is the shape that makes the hair looked clumped like that.
Plus its also with in character design. You can't just make them look cool, you got to keep in mind function, shape, attitude, the pose, etc. You basically conveying information about the character, without words, but just with a picture.