Before you start creating your landing page, think about what your landing page is trying to convey. If you are unsure about your message, the potential visitor will be even more unsure, possibly get confused and move away from the website.
As a rule of thumb, try not to overload your landing page. The less, but still clear information you convey, the better. Keep your message concise and make it clear what you want visitors to do on your landing page.
Your call-to-action (CTA) must be clearly visible above the page break when you open the landing page. It should also match the source you clicked on earlier. If your visitor has clicked on a link that says "Get a free demo now" and is asked to provide credit card details in the next step, your churn rate (rate of visitors churning off your page without completing the desired action; a type of conversion rate) will increase dramatically.
So make sure that the transition from the call to action (CTA for short) to performing the desired activity is smooth and completely transparent - you definitely don't want your visitors to feel trapped.