before we start... you'll need a few things...
1: no moral compass
2: desire to destroy!
3: an evil laugh, examples being... muahahaha! or bahahahaha!

now when you first get in, be evil and skip over the Cell Stage and have all that time they spent creating the stage go to waste! it's the little things that make us cruel.

for the Creature State, you'll want to be a carnivore so you can eat your dead enemies. you don't want to associate with those other filth, instead: kill everything that moves! if you must have a pack use your own species. until you get to the very end, you want to pick three different races before you enter the Tribal Stage so you can have them as pets and you can treat them like your slaves! speaking of the Tribal Stage.

as soon as you enter the Tribal Stage: take no time in gathering stuff. instead, wait until the other tribes gather food... and pillage it from them and destroy them! Muhahahahaha! And don't forget about the evil laugh!

and after destroying every tribe you see, you will most likely be but in a militarist city. in this stage it is your duty to pillage every other city, to do this in the evil method you may do one or more of the following:
1: focus all of your efforts on factory and turn your happiness to helplessness.
2: build a vast army that makes the Soviet Unions army look like the Isle of Mans army.
https://en.wikipedia.org/wiki/Isle_of_Man
3: use a super weapon and blow everything up.

by doing any or all of these, you will dominate the world and make Red Skull proud! and sad that he didn't do it first...

now that your loyal, servants have built you a space ship, you can do two things now that your ideology is conquers:
1: attempt to destroy your own home-world and be a traveling jerk blowing stuff up when you see it.
(thanks for the recharge and repair, pew pew pew.)
2: become the Galactic Empire and basically do the Tribal Stage in space and conquer their territory.
(the Empire with be reorganize into an even... larger... Empire!)
with your path chosen don't make a single ally unless you plan on betraying them apart from one: the Grox, you will be on their good side if you do your evil deeds next to them. speaking of evil deeds lets go through the stuff you can do!
1: blow up somebodies homeworld.
2: make a populated planet unusable with your tools.
3: ally an empire, buy their homeworld, and destroy the shell of an Empire you left them in.
4: no, I don't want to take your stupid cities Random Empire, I want to do the 97th test fire of my bombs!
after you ally the grox, just immediately betray them.

the Space Stage is pretty much a do whatever your diabolical heart desires and use a LOT of super weapons stage. when it comes to making your stuff look threatening, have unity in your colonies and have every building and vehicle be the same shade of black and red with a layer of horns! but the design can vary on what you think evil looks like. you are practically a god, and have the entire Galaxy suffer because of it. tootles and happy conquest!