However unexciting, because PI is my main source of income (and the ability to lose very few ships compared to that), I've had to spend some time redoing some PI. I thought it might be helpful to go through my method with you though, the reader.
1) Decide on a product to make
Before beginning a project to make money with PI, in order to waste as little ISK as possible, you should decide on a product to make. This may not be a quick task however as several things should be considered.
Consideration 1: Make a list of the raw materials you need and which planets can produce them.
Dealing with this consideration will allow you to find a system, or adjacent systems, that contain planets that fit into your scheme. For instance, I decided to make Robotics instead of Enriched Uranium this time. I browsed perhaps 8 systems, and jotted down the planets that were capable of making what I needed. In the end, although I was unable to find a single system capable of making robotics, I was able to find adjacent systems. With only 1 planet in the next system, PI will be less time consuming for me as opposed to being spread out over multiple systems.
Consideration 2: Do the planets in these systems actually have the materials I need?
A good example of this is a Lava planet which has almost no Felsic Magma. If you need Felsic Magma to make Silicon, you'll have to find a new Lava planet, which may make PI more time consuming. Once you have found all the planets you need, with the necessary raw materials, then you can move on without having to worry about it.
2) Setup and Efficiency
Efficiency is pretty key to making easy ISK with PI. However, you don't want to waste ISK in setup.
Consideration 1: Maximal Extraction
As you might have noticed, resources move around. While this solution is not perfect, it is the best I've come up with: a floating extractor with 10 extraction heads linked to a floating launchpad. Yes, while it does cost about a million ISK to move these structures, it more than makes up for itself by allowing you constantly produce as much as possible. After dropping my launchpad for the production facilities, and a linked storage facility to it, I drop the floating extractor and floating launchpad where resources are thickest, not necessarily hottest. Thickness is key, as it will keep you from moving your floating parts too much, thus keeping it efficient . It should be noted that an ECU with 10 heads requires a level 3 upgraded link to the floating launchpad.
Consideration 2: Maximal Extraction with Linking.
Were it not for the floating launchpad, this would be an issue, as longer links require more CPU. Because of the floating launchpad, I can use the import/export system to move my raw materials to the factories. This does cost a few thousand ISK in daily operation, however, it negates linkage problems and negates an ECU producing far more raw material than the Factory cluster might be able to handle. Again, efficient, at the cost of some ISK.
Having dealt with consideration 1, whatever CPU and Powergrid remains gets used in Factories. I personally tend to make 6 basic factories to produce a Tier 1 product, sending all of that Tier 1 product to the storage facility. Once a day I'll expedite a transfer to export the Tier 1 product.
3) Assembly Worlds
Since I only spend the time to get Command Center Upgrades IV and Interplanetary Consolidation IV, I am limited to 5 planets. For any Tier 3 product, 5 planets is either just enough or a little extra. As such, I want to produce as much of the final product as I can, but am limited by the intermediate products.
Solution: 4 Extraction Worlds, 1 Assembly World
In short, the Extraction Worlds produce the intermediate products (roughly balanced, nothing is perfect). This in turn lets me utilize the 5th world to make the final product. A fuel like robotics requires some more intermediary assembly, however, this takes away from the actual making of robotics, so now a new consideration enters play.
Consideration 1: How do I balance the final product with intermediary product construction?
This is a little harder, a little more time consuming. You have to look at what each final production facility will require, then use that to make the required number intermediary facilities. It turns out that 1 Robotics facility requires 2 Consumer electronics facilities and 2 Silicon facilities in order to run full time non stop. Once this is decided, you need to figure out how you can set up as many sets of facilities as you can in a way that doesn't require upgrading links, which take away efficiency, and at the same time are closely packed to reduce the impact of links.
4) Daily Operation
With great ISK comes great responsibility, and as you guessed, this is a daily job. However, it is an easy one. most of the time, you can just pop into a system, use the import/export system to shuffle materials around, reset the extractors, and be golden. Occasionally you will need to also shuttle intermediary products around and import them. However, once the setup is complete, the system mostly manages itself, with the only interaction coming from shuttling intermediate items, resetting extractors, and possibly moving the floating ECU and launchpad. The total time it takes me per day, per character, is roughly 5 minutes, shuttling included.
This is, admittedly, trickier in low-sec because you really have no protection...even gate guns won't save you. Once you get to know the faces that show around the area though, you get a good idea of when you can and can't move your stuff, and the risk is minimalized. I personally find operation in low sec about half as profitable as null-sec. This is balanced by not needing to move an alt into null, not needing to train up the alt very far, and getting maximal time on the main. Since all 3 characters on are on my main account this works out quite well for me.
My null-sec corp buys PI products from us for 80% jita. That puts Robotics down from 44,850 to 35,880. Since I can make 12 units an hour on my assembly planet, I'm pulling 430,560 ISK an hour, resulting in 10,333,440 ISK a day. This calculates to 310,003,200 ISK per month.
Low-sec is roughly capable of making half as much ISK per month, strictly because of resources. However, because it is low-sec, the last thing that you want is to be doing too much PI, ie showing your face much. There is also the problem of flooding your market, so you have to diversify. Given these, while I'm not rolling in 155 million ISK a month, I am rolling in about 70 million ISK a month (per low-sec character). This brings my total income (for my account) per month to about 450 million ISK a month.
I'm pretty sure that in EMPIRE, you aren't making this much ISK with as little time as I am. With half a billion a month, I can afford to lose a few ships a month and still buy plex. It's a pretty damn good thing, isn't it?