You must use your senses to literally hang on to today and now. And everyone is different. Some people ground more easily by touch. Others rub their feet on the floor. Still others carry Redhots or really sour candy in their purse and eat them when they start to dissociate.
Music can also be a powerful grounding technique - or it can make things worse.
Keep some music on hand just to help you stay grounded. Keep in mind, though, that the music that grounds may not be the music that relaxes you. They are probably two different styles of music. One keeps you present while the other mellows and relaxes. The most grounding music may just be the type of music you like the least.