Tip #6, the sweet spot of the lens
Tip #6 for capturing sharper images: The sweet spot.
All zoom lenses have that range where the lens is the most sharp. That range is usually 2 to 3 stops above the maximum aperture (smallest f-stop number) of the lens and it's what photographers call the sweet spot of the lens.
I usually shoot the Canon 70-200 f2.8. Shooting a lens at the largest aperture causes chromatic aberration, an effect that causes edges in the photo to resemble a Pink Floyd album cover. Higher quality lenses have less chromatic aberration but it is still there. I typically shoot at f7.1 or f8 in the studio to capture the sharpest image possible with my lens.