[bavell]

Most of the time you can just `npm install -D @types/package-name` to get the types for that package. E.g. `npm i -D @types/lodash`

[WorldMaker]

I find you generally want the @types/ dependencies in the same package.json array as the related dependency (ie, if lodash is a devDependency then `npm i -D` away, but if it is a proper dependency it generally makes sense to `npm i @types/lodash`). Different project's mileage will of course vary, but it makes it easier for downstream dependencies.

[strogonoff]

As to the remaining cases, a custom definitions file is unfortunately required to avoid compile-time errors.