Below are some of the hard and challenging scenarios in selenium testing which I faced:-
Dealing with pop-up windows
Testing dynamic text or content
How to go about testing Flash
Capturing screenshots, either to file or in some form of a report
Running a test case repeatedly with some minor changes.
Using suites of pre-cooked data or generating it on the fly for Data Driven Testing.
Generating useful test status reports
Setting up Remote Control
Setting up Grid
handling Alerts Popups
Switching between windows
To avoid such kind of challenges you must learn Selenium by the best Selenium course. I am mentioning a Selenium tutorial which you can read to learn more about Selenium. You can also watch the below-mentioned video tutorial to learn Selenium in-depth. .