Hi GetRXd,
You can use the Conditional Warning action to do this.
Here, the Conditional Warning action is checking if the value in the Opportunity Name field is empty (more specifically, "equal to <blank>"). If it is empty, the specified Warning Message will be displayed to the user and no more actions will get processed (in other words, the record will not be saved - this forces the user to enter something here).
You can set up a Conditional Warning action the same way, to check if data has been entered for any field on screen. Conveniently, the other Save buttons on this screen (Save & New, etc) are set up to reference this Save button, so you'll only have to add your actions here to affect all of them.
If you would like to hire a member of our Professional Services team to do some customization for you, let me know and I'll have your account manager reach out to discuss the specifics.
- Justin