Well I started with spellsandmagic.com They have some really good advice on casting spells. I also would suggest learning as much as you can about magick, such as the elements, different deities, chakras, meditations, circle casting, how spells work, moon phase, planetary hours, tools in witchcraft,basic witchcraft history, Wicca, rule of three/karma, divination, fluffy bunnies, energy flow and control, and astral projection. That should be it.
Definitely DO NOT start with spells. They will not work if you just jump right into spell casting without knowing the basics first. This happens with a lot of newbies, they think the first thing they should do is spells, and when none of their spells work they get discouraged and give up. Inbox me and I'll get you started in the right direction.