buy shampos and conditionar that are made to create volume and also using a big round brush and blow drying your hair from the root of your hair and before that, use a volumizing moose before adding the heat and if you don't have a round brush you can blow dry your hair to the opposite side that you normally wear it so say you part your hair 3/4 to the right you would blow dry your hair to the left to create some hight so it doesn't fall flat
I have fine and thin hair so I know how you feel. I do a couple things to get volume. This sounds weird but rinse your hair with flat room temperature beer. Any beer will work as long as its a light color, rinse it through your hair in the shower then shampoo and condition the ends only. The beer removes build-up and residue. Also I blow dry with a round brush right at the roots and pull upward. These really help me. Good Luck!