Consider whether an existing services repository can be used. Note you should be thinking 6 weeks ahead of deploy about when and how you want to deploy this.
It has got most of the things you need to get started - it exposes endpoints, and it's easy to add your own; it allows you to interact with RESTBase and the MW action API in an easy manner; and it also has a load of goodies that come in handy once the service is in production: a streamlined build and deployment process, logging and metrics collection, scaling, etc. You can read a bit more about it in the documentation.