Quality is not an act, it is a habit.
Different automation pitfalls appearing in modern web applications are described and emulated below.
Make sure you are not recording dynamic IDs of elements
Check that class attribute based XPath is well formed
Verify that your test does not interact with elements invisible because of z-order
Ensure that a test is capable of waiting for a page to load
Some elements may appear on a page after loading data with AJAX request
Event based click on an element may not always work
Entering text into an edit field may not have effect
Scrolling an element into view may be a tricky task
Verify cell value in a dynamic table
Finding an element by displayed text has nuances
Follow the progress of a lengthy process and continue upon completion
Check if element is visible on screen