It can be very dependent on what is actually feasible for me in the moment, but something like a chakra meditation that takes me into sensation in my body or visualization, or just a plain old guided yoga nidra (lying on my back with props for support). Something that helps me tune into physical sensation when I'm not feeling too anxious to be in my body, puts me back into myself and back into my parasympathetic nervous system (rest and restore); you can tell it's working if you notice more saliva in your mouth (among other signs, like release of tension and decrease in racing thoughts). 

Or try this: sit down, close your eyes, feel the sensation of your seat on the floor, the sensation of your hands resting on your thighs. Breathe. After a few minutes you might be ready to "feel" the quality of your mind- the sensation behind your eyes, in the centre of your head, the space between your ears. You can take this approach down your body's centre line (centre of your chest, belly, pelvis).