Have you done any research yourself on witchcraft? There are some books that, even though most are sometimes on the Wiccan or Pagan religion, they do have the basics on starting off.
Learning how to ground and center yourself is a start. There are some great articles on the website that go in depth and have exercises on it. Then, meditating will be good too. You can first center yourself, then ground your energy and meditate while at it, grounding is a form of meditating but learn about both so you will have a good understanding of them both. For your spells, visualization is what will really help with your spells as well.
If you don't want to read books, the website has a lot of articles that will help on different subjects.