If you have long hair, and you wash it in tangles - without combing it - then you could be doing some damage to it, unless, of course, you like the tangles. This is because washing tangled hair without combing it to remove the tangles actually worsens the tangles.
If you habitually wash your hair with very hot water, then you could be harming the sensitive skin on which the hair grows, and by extension destroying your hair itself. Water for washing hair should be warm or cold. If you can, start washing your hair with warm water, which will rid the hair of (old) oil on it, and then finish the washing with cold water if you like it shinny, as cold water is known to be very effective at bringing out the shine in the hair.
If you apply the shampoo directly on the hair (rather than on the scalp), then you could be messing up with it. The shampoo is actually meant to be applied on the scalp and lower ends of the strands, and not on the upper part of the hair 'strands.' Focusing the application of the shampoo on the upper part of the hair strands will not only cause it (the hair) to weaken and come off easily, but it might also cause your hair to be unpleasantly entangled.
if after washing your hair you dry it by pulling at it (probably in
a bid to save time), then you are not doing it any good. Squeezing the
water you have used in cleaning the hair should suffice in drying it.
You don't really need to pull at it. Hair, as you probably know, is
extremely delicate when it has just been washed, and pulling it will
mean parting with some of. The effects of doing this once or twice might
not be noticeable, but in the long run, the cumulative effect can be
very unpleasant. Washing your hair properly will help to stop any hair loss.