In many studies of magick, you will find methods to protect oneself spiritually. Even in ritual, you cast the circle after cleansing the area with sprinkling salt and water.
Many pagans/witches also ‘draw’ the circle with a wand or athame, empower a line drawn so that no negative energy enters the sacred space. The use of incense (fire and air) also travels at the perimeter of the circle, enclosing all within in a ‘bubble’ of shielding.
As I’ve mentioned previously, you don’t need tools. However, you do need a strong and focused will. (This is why I encourage meditation). Drawing with just your finger, while visualizing energy to make the circle can be enough.
I sometimes use focused visualization, but I will still use the incense because I love the smell of Sandalwood. Bear in mind that whatever works to help you switch into the correct mindset is fine.
Another method of shielding is creating a guardian. This uses a small statue or figurine, or even a rock, which you empower with your energy to give it its own elemental personality. This will then guard the area.