First of all, when you're washing your own hair, you need to apply the shampoo through your roots first. You need to massage your roots with the shampoo. The ends are going to be secondary. The shampoo is always going to go through your hands, so you don't need to actually put the shampoo at the ends and wash the ends. You need to put the shampoo on the top, and then you make your way down by massaging your scalp.
Don't overuse shampoo. Or don't overuse a shampoo that's too drying for your hair. It depends on the hair type too. If you have dry hair or oily scalp, you want to use the right shampoo for that. Choosing your shampoo is really about your hair type, your scalp type. It's not something that you can just go to the store and be like, "I'll take that one." You have to do a little bit of research on your hair. You might want to go to a hair salon and ask a professional to tell you what kind of hair you have and what kind of scalp you have.
How often should you wash your hair? If your hair is oily, you might want to wash it every day. If it's dry, you might want to do every other day or every three days, because the natural oil will actually cover up the whole thing.
There are so many different hair types, and also you have to keep in mind that your hair can be colored, so you might want to use a shampoo for colored hair. The more you try shampoos, the better you will find your own that will work with your hair. The only thing also I will say is don't use one shampoo. Have two or three shampoos in your bathroom, so you can actually use one, one day, and the next day you can use a different one. That way your hair won't get used to the same products.