Request: Spell (Spl) Making Guides and Recommended Tools

I need to start making more complex spl files and I've more or less reached my limit of what I can do with Near-infinity or what I believe I can do with it. I wish to ask this from those more experienced modders. Is there some spl making guides available that you can point me in the direction of, and are there different tools I need to start making spells and spl files? Thanks.