I support what cee cee said but with only one exception: do not sit at or near the rear of the aeroplane as any turbulence is accentuated by elevator and rudder movements. Best place is nearer the center of the aeroplane.
Having said that, and I'm sure you've heard it before, aircraft are built to handle turbulence. Think of it more as a fairground ride and enjoy it rather than worry about it. It's fine and the aeroplane will not break up. The likelyhood btw is that you will most likely have a turbulent free flight anyway. Pilots do their utmost to avoid any known areas of turbulence in the interest of passenger comfort.