Always place flush with the top edge of the design and aligned with the left margin.
Use standard margins, or set the margin equal to 1/4 the width of the box logo as a good guideline.
For landscape layout, the logo width should be equal to 1/5 the width of the page. If portrait layout, use 1/4 the width of the page.
In some instances, like very small banner ads, the logo may need to be larger scale to be legible. Similarly, on a very large display panel, where the logo needs to be the focus point, the scale of the logo may need to be larger than 1/4. Please use your best judgment for visual balance along with these guidelines.