Users should be able to simply, quickly, and intuitively use your product (web/app). Here are my 10 web application usability design guidelines to maximize your product usability:

1. Have a Consistent and Standardized UI
2. Guide the user
3. Make Interactive Objects Obvious
4. Give Feedback – Both for User’s Interacting and Progressing
5. Never Have Users Repeat Anything & Keep Sign up Info to a Minimum
6. Always Have Default Values in Fields and Forms
7. Explain How the Inputted Info Will Be Used
8. Don’t Have Mass-Delete Buttons
9. Have Clear and Explanatory Error & Success Messages
10. Include a Clear Visual Hierarchy and Navigation