We often advocate for "stacked" forms vs. multi-column forms. Here is some research that reinforces that. Stacked forms are completed much faster than side-by-side fields.
There are a number of best practices when it comes to creating forms on your landing pages.
Fewer fields increases conversion rate.
Avoid conversion killering fields like address unless you absolutely need them.
Add qualifying questions only to increase the quality of leads.
"Submit" is not a proper call to action.
No best practice is best for everyone, though. This infograph does a great job of putting some numbers behind the development of the right form for your landing page.
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