My coolant producing facilities on a Storm planet in low sec are working quite well and with that handily under control I decided to add to my empire by creating a sister colony on a barren planet to produce mechanical parts to add to the POS fuel generation. While the amount being produced every day is small right now as I ramp up production, its very easy as I don't need to visit the planets in order to manage them. That's +1 for CCP.
I'm debating where to expand to next. I could either get two more planets to produce coolant and mechanical parts on and go from there, or I could look at producing Oxygen or Enriched Uranium. Oxygen is easy being a P1 product and requiring only one resource, but Enriched Uranium would require a rarer Plasma planet for both heavy and noble metals or two planets for the extraction of the resources. I'll have to see what is available nearby.
Another option is to go for the Robotics production. Being a P3 product it will probably require at least two planets, one for producing more mechanical parts and another for producing consumer electronics. I think I might leave that effort for another day as I don't want to overwhelm myself with PI work.
To help my planning I've been making extensive use of the PI Tools website of the 4WARD Inc corporate website. Highly recommended.