You know that friend who tells a story and goes off on seventeen tangents, until you're thinking "wait, what was the point?" Don't be that friend in your copy.
Here's the deal
Every piece of copy needs one main idea. One primary benefit. One core message. Not three. Not five. Definitely not "everything we do, because we're brilliant".
Your product may do a million things. But try to communicate all of them at once and you communicate none of them well. The reader's brain turns to scrambled eggs.
Ask yourself: what's the one thing you want them to walk away knowing? What's the one problem you're solving? What's the one reason they should care?
Everything else in your copy supports that one thing. Features, testimonials and guarantees are the backing singers. Your main benefit is the lead vocalist.
The big phone brands do this brilliantly. A smartphone does a thousand things, but each advert focuses on one: the camera, or the battery, or the chip. One message. One landing.
If you can't sum up your message in one sentence, you don't have a message. You have a mess.