For the bleach, I'd try a calligraphy pen. Much finer control over how much you lay down. Also there is a difference between a dry shirt and wet shirt. It will probably kill the pen, but the control is nice. A syringe will work too, but it's more awkward.

And of course, remember that bleach takes a few seconds to "develop".

Something I haven't tried with bleach is masking it with a stencil or wax like a batik. That could be really cool, like tie-dyeing but in reverse.