Best and cheapest maybe different depending on what you consider best.

The easiest is to simply buy Award Accelerator from the comfort of your couch. In a few minutes and a little over $1000 you would have your 8000 PQM (and 8000 RDM too). Is it super easy, but costs.

The cheapest is to find convoluted routings for your upcoming flights. I don't know where business takes you, but instead of nonstops try to route through other hubs, the more distant the better. No cash cost (or only a little in fees) but you pay in time and inconvenience.

In between these extremes, there are MRs or mini-trips, as already suggested by others.