This is a very individual question and it is impossible to give a simple answer. Everything depends on your specific needs and your application usage pattern.
This article and the film included in it present some best practices and might be very helpful when deciding how to configure requests and limits in your particular kubernetes cluster.
Before taking decision about configuring limits you should observe your cluster behavior for some time. Tools for Monitoring Resources are excellent source of such information.
To scale an application and provide a reliable service, you need to
understand how the application behaves when it is deployed. You can
examine application performance in a Kubernetes cluster by examining
the containers, pods, services, and the characteristics of the overall
cluster. Kubernetes provides detailed information about an
application’s resource usage at each of these levels. This information
allows you to evaluate your application’s performance and where
bottlenecks can be removed to improve overall performance.
top pod
to get the idea about sensible defaults. – Egor Stambakio