Summarize the following:
If you have fine or thin hair, using a volumizing shampoo and conditioner can help give you bigger hair. They cleanse and moisturize your tresses without weighing them down, so your hair appears fuller and thicker. While fine or thin hair needs moisture too, using conditioner at the roots can weigh down your hair so it looks flat. To get more volume, only apply conditioner to the ends of your hair from the ears down.  If your hair isn’t particularly dry, you don’t necessarily need to condition every time you wash your hair. Using conditioner every other time may provide all the moisture that you need and leave your hair looking fuller. Put a little conditioner in the palm of your hand, then use it to gently scrunch the ends of your hair. This way, you can moisturize your ends without weighing down the rest of your hair. If your hair and scalp tend to get dried out, your scalp may compensate by producing more oils, which can lead to a flat look. If your hair tends to get limp and greasy at the roots and dry in the lengths and tips, try switching to a gentler, more hydrating shampoo. Try washing every other day instead of every day to give your hair and scalp time to rebalance. Hair that is healthy and hydrated will look fuller than dehydrated hair.

Summary:
Choose a volumizing shampoo and conditioner. Apply conditioner in the right area. Avoid over-washing to prevent dryness.