I'm not an expert or a designer. Your users will show you how to improve the design because you'll see evidence of where they're getting tripped up. For example, if a certain page is the last one most people see before leaving the site (other than front page), then you can tell that page A) solves a problem, or B) causes people to lose interest.
A good starting point is to look at other language sites and decide which ones seem friendliest and least friction-y. How easy it is to get started?
As examples, I really like Rust's website[1], and Elm[2] is pretty good, too. Rust's site is great because it's readable, all the important stuff is above the fold, and it has big action buttons. They also give a fairly long example of syntax, which is important.
I've even seen some languages that will show a snippet of code in an existing, comparable language, along with that same snippet translated into the new language. That's a great way to make your language accessible.