Folks at Cloudflare describe how they work with Terraform there.
This article contains some examples of using Cloudflare's Terraform provider, so those might be handy if you're using their product.
Also, there's a controversial opinion about the usage of Tf modules. This article claims that one should avoid modules, because they decrease clarity in the long run. Like, if you have multiple environments or accounts, or applications that are similar but slightly different from each other, the cardinality of modules' variables may become unbearable.
I won't comment on this. I think this is one of those cases, when context matters the most. Such an approach may suit you or may not. You need to decide whether you'd better use modules or not yourself.
#terraform