Good copywriting is always helpful. Think about it this way, you want to hit on a beautiful girl - you have to know how and what to start with until she says yes to be your date, right? It is the same thing here, you have your landing page to open a conversation with your prospects (buyers) to get a big yes (sale) from them.
Good landing page must have:
1. Good headline which doesn't sound too clever or like a title.
2. Sub headline - you already have a good headline now they are interested to read more, hit them with your awesome sub headline.
And the list goes on. This has a lot to talk about but it will be fun to you to learn about this as it will be your lifeline for your new venture.
Good luck with that.