Okay, so the folowing apply to every spell, not just the big ones.
2)cast a circle for protection
3)call angels for protection
Meditation is just clearing your head of everything. You cannot teach it, but there are guided meditations.
Channeling energy? I don't really know how I got that. It's just a thing... Don't really know how to explain... Sorry.
To channel energy all you have to do is imagine the energy that you want to move as some sort of light (usually white) and just use your imagination and visualize it moving wherever you need it to go. I recommend moving your hands with the energy as some sort of aid or to help you visualize where it's going easier. It's really easy and you can usually feel the energy as some sort of tingly sensation.