You are not smarter than an operating system's memory manager. You won't know if a process suddenly has a memory leak, and the page file cushions the leak. If you try to manually handle processes, but you're off playing a game, your computer is just gonna crash because it has to wait for human intervention.
The most a process can do is suggest to the operating system to keep its functions in physical memory. For example, in VMware VMs, this feature is called memory overcommit. But, the operating system is king. If the OS itself needs the memory, it WILL kick things to the page file is needed.
The fix you need is simple: Get more RAM.