RULES OF GOOD DESIGN
Items on the page should line up with one another appropriately.
Don't center-align everything; left alignment is often a cleaner look because it creates a stronger line.
Visual Hierarchy :
Emphasize important elements.
Organize content logically and predictably.
Use layout to lead the reader's eyes through
Avoid distracting, unnecessary graphic elements.
Don't make everything look equally important.
Elements on the page should give a sense of equilibrium or wholeness.
Use an appropriate proportion of text to graphics.
Use colors to create mood or style.
Create balance around your page's focal point.
Repeat certain elements throughout a design (e.g., navigation bars or logos) to provide consistency, which helps tie the design's pages together.
Keep repeating elements in the same place from page to page.
Keep some consistency of design from page to page (including fonts, formatting, use of headings and graphics, etc.).
Items placed closely together appear to be related or connected in some way.
Group together those items that belong together.
Remain conscious of the white space between page items and of what that space implies.
Provide variety within a design by utilizing different colors, shapes, sizes, etc.
Always make sure the foreground text has good contrast with the background.
Use contrast to set off the various elements of a design (e.g., distinguish a sidebar or navigation bar from the rest of the page using a contrasting color).
adapted from adobe.com