Education: Gear for Your Brain
I have dedicated an entire bookshelf page to my very favorite lighting (and other photo) books for your consideration. All are well-considered and are, I believe, the very best examples in their genre.
But beyond that I would suggest you consider the occasional workshop. Nothing beats a hands-on, small class with a solid pro who knows things you would like to know. It is a super growth experience, and something you really owe yourself if you are passionate about learning to be a better photographer.
At this point severe time constraints limit my ability to teach. But in the past I have taught many workshops and worked with many organizations. Having worked as an instructor for Gulf Photo Plus (held late winter in Dubai) and Santa Fe Workshops (held year-round in New Mexico and elsewhere). I can strongly vouch for both of these organizations. I have seen first-hand how students grow in leaps and bounds in the span of a week, all while making great new friends and having the experience of a lifetime.
If you have ever toyed with the idea, you should definitely ask around, do your research and then take the plunge.
That's it, For Now
That's my two cents worth on gear. You may have other choices or priorities, but that is the best I can offer you with 25+ years' experience behind it.
If you want to chime in on your own, feel free to do so on Twitter via the hashtag #StrobistGear. If is it important that I see it, include an @Strobist in there somewhere and I will.