Because lead generation is the first step of the sales process, both quality and quantity are important factors. Quality leads are leads that a salesperson has a good chance of closing, which means they must at least have the potential to become customers. Every lead list will have a number of junk leads – people who are not qualified to buy the product for some reason – but the smaller the percentage of bad leads, the less time salespeople will waste while processing that list. Quantity is also important because even a salesperson with a list of 100% good leads won't be able to close every one of them.
If links and looks are set, begin interacting with the page. Abandon it, adjust the window size, convert. Are error messages appearing when they’re supposed to (if, for example, you don’t input all the form’s required info)? Is your CTA button working? If you abandon the page, are you retargeted with ads? When you resize the window, does your landing page respond accordingly?