The primary task that I'm playing with now is to maintain a continuous central channel connection from top to bottom and to conduct as much energy/electricity through it as I can. The question of contraction vs. relaxation, or breathing vs. not breathing, continues to be less interesting. Not-breathing is sustained by a focus on it, so I just let it do what it does; it's sure not to stay the same, so I don't need to babysit it. Whether a link in this vertical chain contracts or relaxes doesn't dictate whether it can conduct energy. I picture a bunch of people lining up (kind of like the vertebrae in my spine?) and focus on maintaining the physical connection between them. As long as they're touching, the electricity can flow through the entire chain. Whether or not an individual in the chain is covering their eyes and ears and holding their breath doesn't matter so much. But once the energy is flowing, they'll eventually take a peek and see that it's safe to look around, breathe, and relax a little.
I'm also operating under the assumption that there's no real limit to the intensity of energy I can experience. At each new threshold, it's my choice either to retreat or expand. My confidence is growing such that I'm choosing retreat less often.
When the energy pools in my head and I don't feel much else, there's a technique I'm starting to use which seems to work. I make the assumption that I'm resisting somewhere below my head (in my throat, chest, etc.), but I can't actually feel the resistance as a contraction. So I voluntarily contract so as to begin to feel it, which enables the energy to travel further down, even if the "chain" is tight or contorted. Once I feel the energy, I can shift my focus away from the contraction to the energy itself. It's a provisional contraction, like scaffolding for a tower that's under construction. Once the building's elevator is even barely operational, I can let the scaffolding drop away.