The best thing to do when you’re starting is to do lots of research. Look into the different philosophies and religions under the pagan umbrella. Talk to witches on tumblr, get a first-hand account of their practices if they’ll allow it.
Read blogs and articles and field guides about herbs and trees. Gain an understanding of basic biology, chemistry, and physics. Develop a base of practical knowledge in addition to magical theory and spells. It doesn’t have to be encyclopedic; you just need a basic understanding of how things work in the physical sphere in order to work effectively in the metaphysical one.
Discover why there is no such thing as “black” magic and why there are some formerly common words (g*psy, spirit animal, smudging, totem, chakra, karma, etc.) which you should never use improperly again. Learn about cultural appropriation and why you should never, ever do it. Become aware of the social issues facing the pagan community. Make yourself socially aware and socially responsible.
Learn about yourself. Discover what speaks to you. Develop your own set of beliefs, your own set of practices. Understand and accept that these can and will change as you continue to learn. Understand that witchcraft is a practice, not a religion, but that you can apply religion to it, if that is your wish…