I don't think anyone knows how you become a VIP. There is no becoming a "VIP member" as far as I can tell. One visit you're a VIP, the next visit you may not be.
I can tell you the first time we were VIPs, we were at the RPR. We had had a crummy stay at the PBH and were offered a free night to come back. We turned it down as we had no interest at the time in returning to the PBH. Since we turned down a free night at PBH and made our ressies at RPR instead, the RPR manager at the time sent us champagne and chocolate covered strawberries and left us his business card leaving us instructions to contact him should we need anything. That's where we first noticed our room number on the VIP chart on the housekeeping cart.
After that, we loved the RPR. We only ever stayed RPR Club, and we developed friendships with the staff there. We probably earned our VIP status there through several stays, positive feedback, keeping in touch with staff, gifts to them that the club manager always made a point of showing off to "upper management" as she liked to call it, etc.
At the HRH, I believe we were VIPs simply because we were Platinum and paid a qualifying rate. At any rate, we received nothing extra that we would not have received otherwise for being Plats.
I can tell you that the only thing I've noticed in being a VIP v. non-VIP is our room location and/or view have been better when the views have been variable when we were VIPs. When we weren't VIPs and the room views/locations were variable, then our rooms didn't have the most desirable views/locations (e.g., RPR Club, HRH King Suite).