The short answer, for a server, is buy and install more RAM.
A server that routinely enough experienced OOM (Out-Of-Memory) errors, then besides the VM (virtual memory) manager's overcommit sysctl option in Linux kernels, this is not a good thing.
Upping the amount of swap (virtual memory that has been paged out to disk by the kernel's memory manager) will help if the current values are low, and the usage involves many tasks each such large amounts of memory, rather than a one or a few processes each requesting a huge amount of the total virtual memory available (RAM + swap).
For many applications allocating more than two time (2x) the amount of RAM as swap provides diminishing return on improvement. In some large computational simulations, this may be acceptable if the speed slow-down is bearable.
With RAM (ECC or not) be quite affordable for modest quantities, e.g. 4-16 GB, I have to admit, I haven't experienced this problem myself in a long time.
The basics at looking at the memory consumption including using
top, sorted by memory usage, as the two most common quick evaluations of memory usage patterns. So be sure you understand the meaning of each field in the output of those commands at the very least.
With no specifics of applications (e.g. database, network service server, real-time video processing) and the server's usage (few power users, 100-1000s of user/client connections), I cannot think of any general recommendations in regards to dealing with the OOM problem.