I’ve been banging on about simplifying website forms for years, and I hope you’ve been able to take on board this accepted wisdom. If you wouldn’t ask someone on the telephone for unnecessary information, don’t ask them for it on a website.
That’s the biggest hurdle in increasing website form completion rates. However, with the explosion in screen sizes of the last 10 years, the visual design of forms has become nearly as important. People may be prepared to screw up their eyes to read a non-mobile-optimised website, but they won’t fill in a form they can barely make out.
With that in mind, examine the forms on your website on different devices, and ask the question: “Is this easy to complete?” Most web designers have the toolkit to create something pretty decent, if only they’re asked. If you really want to improve things, have a read of 46 Form Design Best Practices on Noupe, which is one of the most comprehensive roundups I’ve ever read of what you should be considering.