Pick up one of the witchcraft books you have, or get one of the free for a day ones that end up being on my blog from Kindle pretty often. Read it and do the exercises, do a few of the spells, do some of the rituals and then tweak things from there to personalize it if you need to.
All of this as well as using a bit of critical thinking.
In my opinion, emphasis needs to be on “a bit”. Critical thinking is vital for the witch, but get started witching at some point. Tearing apart texts has become more fashionable than actually doing the work. Striking a balance is vital. For me the balance is weighted heavier on the doing and practicing side—though I am not going to assume everything I read is true facts.