1. Brows should start above the inner corners of eyes. Tweeze stray hairs on the bridge of your nose in the direction of hair growth.
2. Tweeze stray hairs below your brow following your natural brow line - the peak should be directly above the outer edge of the iris (the colored part of your eye).
3. Brush hairs up and outward to reveal spots that are sparse. Fill in with a pencil using light, feathery strokes.
4. Brush hairs up and outward again so they are neat and look even. Then set them with a clear brow gel.

The key to this modern brow is to keep the width the same throughout the entire length and slightly taper the outer tips.
So to shape and maintain your brows, follow their natural lines. If you don't have an arch, you shouldn't try to create one - you'll only make it too high.