Shampoo is hair-washing detergent. Its main mission is to clean your hair, removing dirt and the natural oils that accumulate in unwashed hair. Since the main job is to clean your hair, not add body or volume or shine or bounce or manageability, your shampoo should not leave anything behind in your hair. When you rinse it out, your hair should be clean. If you don’t know what clean feels like, try washing your hair with dish-washing liquid. It may be a little harsh, but it will give you the experience of what clean hair feels like. Once you know that feeling, buy the cheapest shampoo you can find that gives you that feeling. Don’t use shampoos that include conditioner. The job of leaving something behind in your hair is at odds with the job of cleaning your hair. It will do neither job well. Don’t do it.
After washing your hair, if you like it when it is dry, you are done. Style it however you like and go about your day.
If your hair becomes frizzy or limp or flat or dull or anything you don’t like, you can add product to it to make it more likable. Don’t use rinse-out conditioner. Why would you add something to your hair to obtain a particular effect and then rinse out 90% of it? Use leave-in conditioner. Use whatever conditioner you like. It doesn’t have to be the same brand as your shampoo. If you just want to be able to get a comb through it, try a little olive oil. If you don’t want to smell like a Mediterranean deli, try something with a smell you like. Keep in mind that whatever you put in your hair has to come out the next time you wash it. If you use product that binds to your hair, such as products that “repair” split ends, you will have a harder time washing them out.