Tips to make your design more impressive.

As a designer we always strive to make our design to look more professional and creative. It might be website, logo, business card, book, advertisement or even may be TV animation doesn't matter. Design principles or tricks are very generic and it will apply to all.
I have few tips which might help you to improve your design better.

• Use colors to create emotions
• Use limited number of colors if possible.
• Keep proper contrast for texts.
• Use grid
• follow some grid system while organizing elements.
• 960 degree grid or custom grid can be used for web design.
• Vertical rythm
• Make sure that follow vertical rythm theory for your design.
• Use images
• Use images wisely.
• Use texture
• Add some subtle texture to background.
• Use subtle Gradient
• Use gradient to create some depth.
• Keep eye direction in mind
• Guide eyes. 
• Use inspiration
• Keep looking at latest trends and inspirations.
• Learn from other great designs.
• Don't decorate
• Don't add color, gradient or texture as just decoration element.
• Use white space
• Add white space wherever required.
• White space creates breathing space in your design.
• Use hierarchy
• Create hierarchy in your design using size, color, image.
• Keep copy simple
• Use simple and elegant words.
• Use good font
• Use good font available for your theme.
• Use shadow
• Use drop shadow to create depth feeling.

As designer you might have additional suggestions. Let me know in your comments.