Witchcraft spells are becoming more and more popular and the Internet is filled with sites loaded with free information on spells. The "free spell books" can be easily found almost everywhere online, and that can make it hard to pick one spell to start with. And if you do find your spell you might actually have no clue about what to do with it next.
So here are some guidelines to help you get out of this mess of confusion and start casting your first spell.
First, if the spell will result in a change for the worse - a negative outcome, then don't get involved with it. The witchcraft three-fold law takes effect here. It simply states that whatever you put out into the universe will return to you three times as powerful.
The law is immensely helpful if you are performing a positive spell, trying to help something or somebody. But imagine how it could backlash when you're trying to cause harm to somebody, and it comes back to you three times as worse. We are all connected, so keep things in harmony and do good.
My second tip for effective spell casting is to not to try doing it when you're in a negative emotional state - confused or mad at someone, or tired. These negative states of mind will not let you concentrate fully on performing your spell, so in addition to the effect mentioned above you might not even get any results at all.
Set up a quiet space where you can do your spell work, learn to relax thoroughly before you begin, and be prepared. Sit in the quiet for a while, try meditation, breathing exercises, and so on. All of these things will guide you along to the path of spell casting mastery.