Grounding skills help reorient a person to the present to the here-and-now. They are vitals tools to have when you deal with anxiety, flashbacks and dissociation.
A powerful way to help ground is through the use of smell. However, it is important to be aware that smell is also a powerful memory evoker, so choose something that evokes strictly positive memories, or something neutral.
I like to recommend carrying around good smells to help ground yourself anywhere. This could be by way of scented lotion or hand sanitizer, a scented candle, smelling flowers. Or you can also stop and really try to notice the smells in your environment and then name them, either out loud or to yourself.
The naming is important as it helps reinforce what you notice and be more mindful of it, not just speeding through and maybe not having it register.