So you really want to get the healthy hairf those shampoo advertisement models have (seriously, is that real hair or is that a nylon wig?). If your hair is naturally healthy, there's nothing stopping you from getting the nicest head of hair. You just need to make sure that you aren't making any really obvious mistakes. Try to see if any following mistakes seem familiar.
There was actually a TV advertisement for shampoo a while ago in which a mother looks at her five-year-old daughter reaching for the shampoo and asks her if she didn't shampoo only the day before. To which the child smartly answers, "Well, didn't I see you reach for the toothpaste yesterday?". The implication being that just as you need to use soap on your body everyday and toothpaste for your mouth everyday, you need to shampoo your hair ever day too.
While that sounds very nice, it really would hurt your chances of trying to get healthy hair. No more than twice a week is what the experts say. Because your hair needs the natural oils your scalp makes. It just won't do to use shampoo to wash it all off all the time.
People can be creatures of habit. You might have a wide open space in front of your house; but you'll still choose to walk the same route everyday. People do that with their hair too. If they need to fasten their hair in a ponytail, they'll always use the band on the very same spot. Try to use seamless elastic, and always make sure that you don't use the exact same spot all the time. You don't want strands from the same spot getting caught in the band all the time.
One wonders where the "brush your hair a hundred strokes every night" thinking about maybe it started with that Brady Bunch daughter. But that much brushing doesn't do your hair any good. Certainly, you don't have to be like one of those people who have hair brushing syndrome (yes, that's a real thing where you can die if you brush your hair). But you don't want to overdo it either. Brushing is good because it helps spread the oil manufactured by your scalp. Too much brushing and you'll just wear your hair down.
Try not to ever blow-dry your hair for any longer than 5 min. a day. Just because your hair doesn't feel pain, doesn't mean it doesn't get damaged. Too much heat is not the way to get healthy hair.