A few questions about my hair?

Is there any special way that you are supposed to wash ur hair? Like starting from the top or bottom? Is there any great shampoo that u reccommend? I use Finesse mosturizing shampoo and conditioner. I used to use Loreal Vive Pro body and style infusing shampoo and conditioner. Are these good shampoos? I have straigh, thin-ish hair. I sometimes use the CHI straightening iron to fix my hair. do u kno any tips that would help my hair? Thanks in advance♥