Dyeing is a lot like cooking. There are recipes for cooking. Pick a recipe, assemble the ingredients, follow the directions and you should have something resembling the mouth-watering picture on the front. I'll admit that often it's not as easy as all that. But the fun part about cooking is that the recipe serves as a blueprint for other adventures in cooking. Take that same basic recipe and you can tweak it to your own taste - more spice, less salt, add this, omit that. Before you know it, you've created your own recipe. The possibilities are endless.
The same goes for dyeing. Start with a basic color recipe. Yellow and blue make green. There are many ways to refine that basic green color. A little more yellow gives you a moss green. A little more blue gives you a pine green. As with cooking the possibilities are endless. And that's half the fun.
Tweaking a basic color recipe can have subtle or dramatic results. I've been playing around with colors for a custom dye job. A little more of this, a little less of that.