In my opinion, you should just meditate for a few minutes every day, or try to balance all your chakras to get rid of all your negative energy that surrounds you; that are some things you can do to start with all of this. If you want a spell, I highly recommed you to look at the Spiritual spells section - protection, banishing, defence, contact and energy spells.
But as I said, you have to know some of the basics to start with before trying any spell, do not forget it! And, also, the more advance you are with Magick, the better for you. You should be able to cast more powerful pells.
Hope this helped.