For some weird and inconceivable reason you appear on 40k's Terra...

For some weird and inconceivable reason you appear on 40k's Terra, and somehow you gain the power to change the Imperium at your will.
This means you can now reform the bureocracy, give orders to the military, tell the Mechanicus to start developing new tech... Whatever you want done, will be done(in the scope of what's possible). Of course, you retain your 40k knowledge.

What do you do? How do you Make Humanity Great Again?

HARD MODE

You are the new Master of the Adeptus Administratum.
What do you do? How do you put your lore knowledge to good use?

Bump.

Hmmmm

I fix everything.

Send an Inquisition team to wake up Lion El'Johnson on the Rock. Initiate pardons for the Dark Angels for past heresy up to this point and force them and their successors to stop team killing and go on a penitent crusade. Force them to share their Archaeotech as conditions for their pardons. Also, said crusade is to go to the heart of Comorraugh to retrieve the Panecea STC for Roboute Gulliman.

Also surround myself with a harem of Sisters of Battle

Do the same thing but masturbate before the emperor to get rid of my Praise boner

No, that's what the sisters are for.

I use my powers to get in the comfiest life with no one to depend on me.

>Administratum

I use my power of bureaucracy and logistics to cripple the other High Lords and bend them to my will.

Neat. I would not have thought of this.

I'd begin a new founding of Space Marine Chapters along with the creation of hidden Mechanicus facilities dedicated to increasing stockpiles of gene-seed.

The Black Templars would be asked to act as consultants for the creation of many new crusader chapters. (Their advice would not be followed on the matter of Librarians.)
Ultramarines and Deathwatch would be asked to train chapters specialized in dealing with the Tyranids.

Negotiate a prolonged ceasefire with as many of the Craftworlds as possible. Trade worlds for them if necessary.

A bunch of other ideas but not all of them seem like they'd work so well.

I'd reign in some of the Inquisition bullshit, assassinating space marine chapters because they rightly called you a bunch of douchers isn't on.

As much as I think they are team killing assholes the Dark Angels have the right idea, tell them nothing and off them when you get the opportunity.

Speaking of i'd have the Dark Angels publicly rebuked and i'd have them and their successors sent on a penitent crusade (typed this out before noticing ) although the HH and 40k fluff shows that due to the history of their founding the grey knights know but do not care.

The red scorpions would also be rebuked for desertion.

I wouldn't bother with the panacea as it probably doesn't work on warp-based venom plus if my instincts are right the HH series is setting up Guilliman to inherit that special bionic that can heal inside stasis fields anyway.

Straken would be made my personal bodyguard, and I would have myself gene-hanced like inquisitor Lord Hector Rex.

I would push for a temporary Necron alliance via the Silent King.

Mostly would be like that Rick and Morty ep where Rick teaches the aliens that giving people the middle finger is a polite salute.

I would conduct the worst possible choice of action.

Maintaining status quo.

Make a pact with the Chaos Gods and do what no other faction could do, conquer the entire galaxy and usher in finally the 42nd Millennia

I do exactly nothing. 40K isn't grim dark because everyone in charge is simply incapable of doing anything right, it's because the nature of the setting itself forces them to do so. What we see is the best the IoM can possibly do with what it has, and because every single time anyone has attempted to improve things significantly for the human race it backfired completely and totally.

Install a Text to Speech Device on the Golden Throne.

Will you please shoot yourself after?

Get rejuvenat treatment and live for a long ass time.
Set up a bunch of institutions composed of Techpriests from different cults as well as Munitorum engineers etc to encourage cross-cult/adeptus cooperation.
Basically force the mechanicus cults to share around some of their knowledge so there's redundancy in case any one cult gets destroyed or rebels.
Cut funding to the ecclesiarchy, placate them by letting them meddle with the Machine Cult, and placate them by using the extra funding to engage in massive, irreversible science.
The science would be space ships: making them, making them fast, making them sensitive and making them reliable in the warp.

Fuck the webway, that shit's for toadpeople.

Get a ship and become rogue trader ,Baby

Boinics and Augmentation
Wake the Loin
Get those Dark Angel jet bikes
Bring the Scars up to full legion strength
Lead a crusade to find the Khan in the webway.

...

I put the Tau in charge of the Admech and Administratum.

>keeping the secrets of lost technology hidden
The AdMech would like a word with you.

1. Have the Adeptus Mechanicus and Adeptus Astra Telepathica work together to figure out what made the Emperor so great (i.e. how to do that thing with the shamans that made him immortal and have incredible psychic powers and omniscience). Then, make me the new Emperor.

2. Tell everyone about Chaos and the Warp and why it's bad. Then kill and/or send to the Eye of Terror anyone who disagrees. Reassign the Ecclesiarchy and Inquisition to educating and preventing people from worshiping Chaos.

3. Complete the Imperial Webway project so humanity has a safe form of transport through the stars.

4. Figure out how to make new Primarchs and Space Marines. Make sure the Chaos Gods don't throw all the Primarchs all across the galaxy so I can take care of them personally and ensure their loyalty. Reconstitute the Adeptus Astartes into 20 Legions each led by a Primarch with the Astra Militarum underneath them.

5. Promote Creed to Lord Commander Militant of the Imperial Guard.

6. Subjugate the Tau Empire and make them a vassal state of the Imperium. Kill anyone who disagrees.

7. Make a weapon that contains equal parts promethium, fungicide, insecticide, and carborane acid. Send the new Legions with it against the Orkz, Tyranids, and Necrons to make sure they don't kick our shit in.

8. Have the Adeptus Mechanicus study Necron technology once all the Necrons are dead, particularly how they travel through space without the warp. Same for the Tyranids, but also with genetics.

9. Kill all the Eldar who won't ally with us. Then kill those who allied with us because fuck the Eldar.

10. Reconstitute the Warp as the Realm of Souls.

Enjoy being played by the blue commies, heretic.

The Dark Angels are more likely to tell you to just piss off. Also if a living Primarch like Lion'el Jonson comes back, they'll simply say you're a heretic, kill you, and take over without anybody objecting.

I'd proclaim the Dork Angels traitors for all their team killing faggotry

>Tell everyone about Chaos and the Warp and why it's bad. Then kill and/or send to the Eye of Terror anyone who disagrees. Reassign the Ecclesiarchy and Inquisition to educating and preventing people from worshiping Chaos.

That's a horrible fucking idea

The last time the Emperor didn't do that, and instead just told everyone (i.e. the Primarchs) "Don't mess around with your psychic powers because I say so, and if a creepy guy comes up to you in an alley and offers you ultimate power but you have to sell your soul, just say no, once again, because I say so." May as well just explain that Chaos is bad because it mutates you, causes you to do deplorable things, and is fucking evil, and that the Warp gives you magic powers, but is dangerous to use, so be careful and don't summon demons. Then, the Ecclesiarchy and Inquisition can make sure nobody worships Chaos and uses their powers safely and for the benefit of mankind. And if that doesn't happen, kill them.