There are many approcahes depeding upon your intended cost.
Place a good quality shelf under the turntable, such as a Neuance, Mapleshade, or a Black Diamond. You can even go homebrew with a slab of MDF. Then use a sheet of heavy-duty (the pink antistatic) bubble-wrap between your rack & the isolation shelf. This is a proven approach used by some highly knowledgable members here.
Instead of the bubblewrap you can set the shelf atop a set of Vibrapods, superballs, sorbathane pucks, etc. Be prepared to experiment for your prefered sonic signature.
Place a good quality shelf under the turntable, such as a Neuance, Mapleshade, or a Black Diamond. You can even go homebrew with a slab of MDF. Then use a sheet of heavy-duty (the pink antistatic) bubble-wrap between your rack & the isolation shelf. This is a proven approach used by some highly knowledgable members here.
Instead of the bubblewrap you can set the shelf atop a set of Vibrapods, superballs, sorbathane pucks, etc. Be prepared to experiment for your prefered sonic signature.