I agree with the above advice. There are some great tools to quickly and easily build a landing page.
However, it would be interesting to discuss your overall objective.
A landing page is sometimes used as a way to test a concept before you write any code. E.g "Let's see if we can get anyone interested in signing up for a beta before we bother writing any code. If no one expresses interest on the landing page, then we will move on to a different idea." A landing page can also be used to A/B test messaging.
However, it doesn't sound like you are trying to run a test. It sounds like you already committed to building and launching the product (and presumably you are getting user feedback in the process) and that the purpose of the landing page is to just get a head-start on your marketing launch and to build up an e-mail list of interested prospects.
In that scenario, I am wary of the typical landing page being akin to crying wolf because you aren't delivering any immediate value to people who visit the page. Presumably there will be an expense to driving traffic (ads, paid e-mail list, goodwill from friends/partners/media who share the link, hitting your existing e-mail list, etc.) but your conversion rate won't be spectacular and it will be harder to drive traffic from the same sources the second time around.
One option is to deliver value on the landing page before your product is launched. For example, you could put together an educational webinar that is somewhat related to the problem you will be solving with a guest speaker that will be interesting to your prospective customers. On the landing page, people would sign up for the webinar and they could also just sign up for the newsletter/beta if they can't make it to the webinar. A link to an interesting and educational webinar may be shared by small business associations with their members. Because you haven't yet launched a product, it's even easier for associations and the media to share the link without making it look like they are promoting your company.