While Creating your cluster, make sure you enable VPC peering.
VPC peering is more secure, it will save network costs and it has no downsides.
Enabling this will also allow you future flexibility by using features that require this setting. Read more here.
When setting up ScyllaDB Cloud to run in your account (BYOA), make sure you set all your AWS account limits with the needed additional allocations for ScyllaDB Cloud. See Deploy ScyllaDB Cloud - Bring Your Own Account user guide for the needed resources and limits. When setting up ScyllaDB Cloud to run in your account (BYOA), you will not be able to use the BYOA option without confirming you have created the necessary allocations.
Over the lifetime of your cluster there may be cases where your server’s IP address changes or you may need to replace a node or two. As long as your drivers are live it should not be an issue because the driver will learn the new topology and adjust accordingly. However, if the application restarts and it reads the old IPs from the configuration file, it will not find the cluster
Always choose NetworkTopology as Replication Strategy for all your Keyspaces. Using SimpleStrategy will not provide High Availability in case of an Availability Zone (AZ) failure, and will not allow multiple Data Centers(DC) setup.
Read more in ScyllaDB Docs or Scylla University
Use Consistency Level of Quorum for one DC, or Local Quorum for Multi DC cluster.
When creating your Keyspaces, make sure to use the same Replication Factor (RF) you used for creating the cluster. A lower number will reduce the cluster availability, while a high number may place more than once replica on the same zone.
When sizing your cluster, make sure you have at least 50% free disk space for cluster backup and other maintenance routines (e.g: compaction). You can use the ScyllaDB Sizing Calculator to customize Scylla for your usage.