Come up with solutions you think could probably work, not necessarily that will work. Choose the simplest one and then see if it does work when you try to implement it. The solution should not be fancy or elaborate - just add the feature as simply as you can and make sure the code passes the unit tests for the new feature. Make sure the code is clean and is not repetitive. Remove anything that is not useful or necessary.
Different people have different standards and solutions for simple code.
Refactoring the code should be done first if the code is not clean when you start.