How to design a landing page

Most landing pages fail in the first sentence, by describing a category instead of a thing.

First line says what it is.

Not the mission, not the problem. The thing. A visitor who cannot tell what it is in four seconds leaves, and no amount of copy below saves it.
Show it before you describe it.

A screenshot or a ten-second clip does the work of three paragraphs. For anything visual, lead with the picture.
Write to one person.

Narrow beats broad. A page aimed at everyone reads as aimed at nobody, and the specific reader recognises themselves immediately.
Cut every sentence that could describe a competitor.

If a line would be equally true of three other products, it is saying nothing. Replace it or delete it.
One ask.

Download, subscribe or buy. Two calls to action halve each other, and a page with five has none.
Use their words, not yours.

Read the reviews, support emails and forum posts. The phrase people use for the problem is better copy than the phrase you invented.
Name the limits.

Free, no account, works offline, does not do X. Constraints read as confidence and pre-empt the objection.
Numbers where you have them, silence where you do not.

One real figure beats a paragraph of adjectives. Invented traction is obvious and unrecoverable.
Make it work on a phone first.

Most people arrive on one. If the top of the page does not make sense at 375 pixels wide, nothing else matters.
Read it aloud.

Every sentence you stumble over is a sentence to cut. This catches more than any amount of staring at it.

First line says what it is.