ELK configurations aspects for beats

Depending what type of elastic cluster you have (self hosted on prem or as a service from Elastic) and what type of authentication you prefer the following methods can be used to send data securely from beats:

Basic authentication credentials (username and password or cloud.id and cloud.auth)
Token-based API authentication.
A client certificate.

You can also enhance the collected data for filebeat/metricbeat by adding some metadata with processors. Some useful ones are:

add_kubernetes_metadata
add_cloud_metadata
add_host_metadata

For all other configurations details here is the official documentation for filebeat and metricbeat.