Many of use know how to shield, but this is a exercise I use before I do any type of energy work. This is an important basic. Shielding stops psychic attacks, negative energies/entities, negative thought forms, etc.. The list goes on.
Step 1: sit down on the floor, feet flat on the floor, now I want you to breath in deeply, while yoire doing that, visualize you're sucking in white light and when you're breathing out, I want you visualize anything negative, thoughts, stress etc.
Step2: Now, since you're nice and relaxed, I want you to visualize yourself sitting on the floor, notice your surroundings, can you see your spirit guide?v orbs, any type of spirits, you may invite to help you, If necessary.
Step3: Visualize a a bubble around you, any colour is okay, but I would recommend using gold or white, since they represent protection. Feel the energy of the bubble, feel that you're now protected, "know that nothing can hurt you" use all of your mental senses.
Step4: Now that you've done that, I want you visuaize another energy field( preferable red) for protection from your spirit guides, angels, animal guide etc. If you have a look at the net, see if you can see any rips? If you can, repair it.
Know that's you're protected, say thankyou for any spirits you invited to help you. And come back to your normal self.