I would suggest researching about different types of witchcraft and what they deal with. After what you feel is an adequate amount of research you should start with something small like, a protection spell. Be wary of cultural appropriation such as, when using a "smudge stick" don't call it a smudge stick unless you practice the native american belief system (there are other words for it such as censing). Also be aware of fake spells such as ones that claim they can change your DNA.
What I would suggest is learning the basics. What are the basics? They are commonly said to be grounding, centering, and meditation. I would expand it to all of those plus understanding reality from fakery. As well as visulization.
Why are these things important? Well grounding can help rid yourself of excess energy. Meditation can help calm you so that you are in the right state of mind for workings (rituals, spells). What do I mean by right state of mind? Well let's say your really mad then go straight for a love working. Many believe emotions can impact your spellwork. How do you think that will impact what your doing? Centering is important as well. For a better understanding of these things you can both look for links on the site as well as using Google. Google has many free pdfs such as works from Scott Cunningham and Donald Michael Kraig.
Also a few notes; magick can be done without religion. Some are drawn to religion and use it in their practice. Your worldview might dictate how you cast or what you cast. For example, a friend I have believes magick is working with spirits and deities only and everything else is just, "wishing very hard". I have met some people who believe in different variations of karma. The Wiccan version to my understanding is that spells can backfire when you do negitive things. That which is considered, "black magick". Now keep in mind magick does not have color but rather intent. That is simply a way many describe things with negitive intent such as cursing, hexing, and so on.