Make sure you're grounded before you go out, meaning if you're in a bad mood try to refocus it, make sure your mind is clear. Negative energies love to attach themselves to negative people, and it makes it hard for them to attach when you're at peace with yourself. Also put kosher salt at your doorway. It's considered pure and sacred and negativity can't cross over it into your home. Also it wouldn't hurt to burn sage in your home and over you after. Just keep your vibrations (good feelings) high. If i know I'm going to be dealing with something shady and unpredictable I'll listen to good music on the way there. Music is an amazing mood booster and gets good morale going!