Heavier Fabrics Add Volume
Heavier fabrics add volume to a thin frame, whereas lightweight fabrics have a drape that accentuates a thinner frame. It's a good idea to go for heavier wools that hold their form. This body type is not limited to just heavy wools; light colored cotton or linen would also work.
Stay with Lighter Colors
Lighter colors add size to a thinner frame. A nice lighter bespoke suit such as a solid grey would do wonders. Pinstripes may create a longer and thinner appearance, but can definitely work with a light colored fabric.
2 and 3 Button
A tall and thin frame will benefit from a two or three button jacket. A double-breasted suit would also work for this body type because it adds volume to the torso creating a stronger frame.
No vent or single vent is recommended to provide a modest, fuller look in the rear.