NetQos is a product line or suite of individual tools that integrate into NetQos Performance Center (NPC) (other tools can also integrate into NPC)
My first bit of advice is fully understand what each tool will provide you and what access the tool requires to gather that information. The higher the fidelity of the data you require the closer to the data source some of the tools need to be to ensure you are not impacting operational data with monitoring data. (SuperAgent, ADA) requires a span or mirrored port in most cases. (Reporter Analyzer + harvesters + DSA) requires NetFlow, SNMP, and ICMP. (NetVoyant) requires SNMP and ICMP, I suggest also setting it up to utilize IPSLA.
Second, security: Have a plan to secure the systems and ensure data collected and replicated between the management tools is either encrypted or traversing a secure media (out of band or encrypted tunnels). Where possible utilize SNMP V3 with SHA/AES encryption. The same data that can help troubleshoot issues and improve performance on your network can be dangerous in the wrong hands. (I also suggest utilizing single sign on.)
Third, scale: Ensure you are not overbuying for the size of your network. The overall cost of a network management solution can be high, no need to make it higher by purchasing products and services you will not be using.
Fourth, Time: Make sure all the servers, devices and well.. everything on your network is utilizing the same network time. Nothing is more annoying while trying to troubleshoot something on a network than not having your Logs, Captures, Reports and Network Change reports all on different timezones or offsets. (or worse miss-configured).