A man (or woman) who grew up wearing his (or her) hair cut short learns to shampoo, condition and dry his (or her) hair in a specific manner. Now that he's (or she's) older and trying to grow long hair, he (or she) fails to realize that the way you treat long hair is different from the way you treat short hair. It's a similar problem with women who grow up with long hair and decide to suddenly go with a short hair style. They tend to use the same amounts of product on their shorter hair as they used on their longer hair.
There is also the fact that many people just never learned the right way to perform these basic hair care procedures. (I know that I can't remember ever being "taught" how to shampoo and condition my hair.) We go from being infants and small children who are bathed by our parents, to older children who are expected to perform these tasks for ourselves. Typically, there's never much (if any) actual teaching of the right way to do these things.

So, let's get back to the basics and discuss the proper ways to shampoo, condition and dry the hair:
The first step to healthy hair is cleansing. This means choosing the right shampoo and using the right amount of shampoo. Most shampoo formulas are made for "normal to dry hair" or "normal to oily hair". A good way to determine which of these you need is to take a spray bottle with water and lightly mist your hair when it is dry.
Does the water absorb immediately, or does it bead up on the surface for a moment before being absorbed? If the water absorbs immediately, you should use a shampoo for "normal to dry hair" because it has more moisturizing ingredients. If the water beads up at first, use a shampoo for "normal to oily hair". The spray test is usually performed to determine the hair's porosity, but works here because porous hair (where the water absorbs immediately) tends to be dry, while resistant hair (where the water beads up) tends to accumulate more surface oils.
Once you've chosen your shampoo, you're ready to wash your hair. You need to completely saturate the hair with water. This is especially easy to do in the shower as you simply place your head under the spray. Run your fingers through your hair to make sure the water penetrates to the scalp. (If your hair is resistant, or particularly laden with dirt, oils and styling product, it can sometimes repel the water and only appear thoroughly wet at the surface.) Be sure to use warm water, which helps to open cuticle layer a bit and lets the ingredients in the shampoo be most effective, and don't squeeze or shake the water from the hair.
Next, you need to use the right amount of shampoo. Most package directions for shampoo call for a "quarter-sized" (2.5cm circle) amount. These instructions are intended for hair of average length - somewhere between chin and shoulder length. If you have really short hair (shorter than chin length) you should use a little less (a nickel-sized [1.5cm circle] amount). If you have longer hair (length that is past the shoulders) use more (a half-dollar-sized [4cm circle] amount). Rub the shampoo between your palms and apply it to the scalp. Massage the scalp and shampoo until the shampoo forms lather, running your fingers through your hair to distribute the lather evenly then rinse your hair completely (until the water runs clear).
Repeat the shampoo process, and note that the second time around the lather should be much thicker and foamier. This means that the dirt and oils that were initially on the hair have been removed (or dramatically lessened) and that the hair is clean. After a few times of shampooing your hair you'll recognize whether the lather is sufficiently thick to know if you need a second shampooing or not. If you do get a full, rich lather on the first go around, you don't have to repeat the shampooing.