If you want to create successful solutions, you need to have a strong usability which is defined by how easy and comfortable your user can get his/her results by using your software or product.
One of the most important components that are related to the usability are interaction times and user satisfaction. Many people refer to numbers of click when talking about usability which is kind of incorrect. Of course you should not include unnecessary steps in your solution but it is more sensible to add one more click if it reduces the interaction time or the complexity of the system.
Another really important aspect for usable solutions is consistency. If you create a solution make sure that similar elements are placed at a similar position on every single page. The users then know where they can find those interaction elements and therefore the workflow will be faster and the usability increases.
Before you begin with the design or development of the solution check who your target group(s) are and how they can be satisfied the best. Children have other expectations than a manager and therefore the interface must have a different concept, information architecture and visual design. Never forget to put your users in focus all the time and actually nothing can go wrong - except: you chose the wrong target group.
A high usability can be created by simply using the UX workflow which involves the users from the beginning on. You start by analysing who you users are an what they need. Then you create first prototypes that need to be tested (in an optimum manner with standardised questionnaires).
A good example for a useful questionnaire is the SUS (System usability scale) that measures the Usability of your solution compared to many other solutions.