Its sort of a mix of math and a little logic. Some of the things only need a few updates, others like the ladder and robot need a ton of updates, things like the TV screen can go in last because it depends on the satellite and tornado/windmill to run. The only thing you need to do is max 11/12 things, and then the last one should max on itself, keep clicking the first icon over and over and it will upgrade itself, but if you have 10/12 two will not upgrade. The last one I had was a level 8 robot, it upgraded itself and everything maxed.
Hey I just beat it again, once you know it you know it. If anyone wants a set that works I will private message it to you, remember the last thing will not max, you must keep clicking the pipe/first icon after you have 11/12 maxed.
*EDIT* Found the perfect order let me know if you want it*EDIT*