Visibility of System Status

For this app, I can add a loader or time-left graphics when user loading the images.

 

Match Between System and the Real World

The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.

 

User Control and Freedom

Users often couldn't find the "go back"button, it should be very clear and add it to almost every page.

 

Consistency and Standards

Users should not have to wonder whether different words, situations, or actions mean the same thing. 

 

Error Prevention

I can set some rules for the format of user password, try to validate it as the user types rather than waiting for him to click submit.

 

Recognition Rather Than Recall

It’s better to suggest the user a set of options than to let him remember and type the whole thing. The goal is to minimize the application of user memory.

 

Flexibility and Efficiency of Use

For the profile page is not very flexible, maybe add a button for "custom".

 

Aesthetic and Minimalist Design

My image widows are too small for this app. 

 

Help Users Recognize, Diagnose, and Recover from Errors

A check needs to be made if those errors are being explained to the user in understandable language. In the below example, I have entered a fictitious username and password and the error message I got is either the username or the password is incorrect. 

 

Help and Documentation

For some Icon may not be very clear, I should add some frequently asked queries on the same page.