1. Consistency

The user interface should be consistent across the website / app. Identical or same terminology should be used everywhere, consistent colour, layout, capitalisation, fonts, should be employed throughout. The example you see below is what one should avoid doing.

The above examples are the part of the same website. If you notice they look like three different websites using this type of layout across pages confuses the users and is major no no when it comes to design.

2. Usability

Recognise the needs of diverse users and design for ease of use. As a UI designer think about the user, try to be as inclusive as possible to the demographic that the design aims to capture. There are some basic guidelines for a inclusive design one in which people with disabilities don't find it difficult to use your service/product. Contrast is one such area where it's absolutely necessary to have good contrasting text with the chosen colour palette. Adding some informational text helps new users understand what a particular element does. For expert users add features like shortcuts so that they feel engaged and can use the in a more faster and efficient way.

3. Feedback

Always give feedback to the user when they interact with the UI, this keeping users from being confused and unsure if the action that the did worked. Suppose I click a button and It doesn't change or do anything, then I feel like clicking the button didn't do anything. So to avoid such a scenario always keep giving users feedback where necessary. For frequent and minor actions, the response can be modest, whereas for infrequent and major actions, the response should be more substantial. Visual presentation of the objects of interest provides a convenient environment for showing changes explicitly.

4. Make a story

People love stories hence the sequences of actions should be organised into groups with a proper beginning, middle, and end. Informative feedback at the completion of a group of actions gives users the satisfaction of accomplishment, a sense of relief, a signal to drop contingency plans from their minds, and an indicator to prepare for the next group of actions. For example, e-commerce websites move users from selecting products to the checkout, ending with a clear confirmation page that completes the transaction.

5. Errors

Design the interface so that users cannot make serious errors; for example, Gray out menu items that are not appropriate and do not allow alphabetic characters in numeric entry fields. If users make an error, the interface should offer simple, and specific instructions for recovery. For example, users should not have to retype an entire name-address form if they enter an invalid zip code but rather should be guided to fix only the faulty part. Erroneous actions should leave the interface state unchanged, or the interface should give instructions about restoring the state.

6. Undo

Allow users to undo their actions, so that they feel safe performing any action on the interface. This is more of a user experience topic than an interface one, but it's a very necessary one as well.

7. Templates

Whether you're a total newbie or a professional use templates, because the layout and elements look the same, they streamline UI features across the products. Plus, you can reuse the same UI templates over and over, even years down the line. This doesn't mean don't be creative and do something out of the box. It is simply encourage a familiar layout and structure for the end-user.

8. Simplify

Sometimes the best design is no design. Less is more. What all this simply means is try to reduce the amount of content displayed at once. This will improve the user's attention as their cognitive load decreases. Humans can only focus on so many things at a time, so presenting information in small chunks improves the overall visual appeal of the interface.

Conclusions

I hope this brief guide gave some idea about what a good user interface design should and should not be like. If you have any queries , suggestions please feel free to reach out to me.