Emotion: Fear, Hatred, Uncertainty, Distrust, Ridicule
This is the absolutely necessary component for brainwashing people. It must be prevented that people could make a neutral observation, an accurate accessment of the current state, a balanced decision and finally a coldly thought out rational judgement.
All species have made an important observation during their lifetime: You can have a good or bad life, but death is always irrevocably fatal. For this reason alone (and it is a good reason) any threat which could cause or lead to this result is much more negatively viewed than its counterpart. If we have a drug which kills in 10% of cases and gives unbelieveable bliss in also 10% of cases, a solid majority of humans would not take the drug. So you need to have some boogeymans which press the red button in the brain. You could lose your job, you could lose your friends, you could lose your wife, you could lose your life. Don't make trouble, it is not worth the effort.
Fear is nice, but how do we get fear? Easy: Your fear is legitimate, there are people out there who wants to get you !! Yes, you! There are people out there who hate you for no reason at all and every, really every action they do is born out of malice.
There are terrorists out there who kill innocent people on purpose for their heinous deeds. They have no similarity to heroic freedom fighters who fight for a worthy cause. We must support the free-loving people under the totalitarian dictatorship of our enemies, but naturally if our enemies are having insurgency groups in our allied states, we need an authoritarian government to deal with it. Rogue state Syria with its ruthless ally target small, little children with barrel bombs. US forces and their coalition in contrast do literally everything to avoid casualties, if a bomb randomly goes off the mount and hits randomly a building with faceless people inside, it is a terrible, tragic unintended accident.
Distrust and uncertainty, ridiculing
While the former emotions try to inhibit a rationally guided response to situations and people, the decision process itself can be targeted. Everyone knows that you are unable to make and defend a correct decision if you know nothing about the situation, so if you want to brainwash people, you must inhibit the possibility to get this information in the first place.
So you must poison the well. Give conflicting information. Invent own sources and erm, "remove" the original sources. Attack people personally that they are liars, make love with prostitutes and kick dogs, do not spare any mud for your sling. If some negative information comes up, it is always propaganda from (insert current enemy and irresponsible person here). Have a battery of "experts" ready who dismiss claims and ask for a "balanced picture".
If something could be very serious, try to turn it into a laughing matter. Use "conspiracy theory, bullshit, ridiculous, nonsense" and don't spare absurd comparisons.
Mass effect (No, not that game) and conformity.
Persons are such social animals that it is very, very hard to escape social constraints. If you have enough persons, you can put such enormous pressure against single persons that they accept even absurd statements.
The observed love for uniformity in environment who want brainwashed people is not without reason. First, people who do not like or distrust the brainwashing message will be rebellious and therefore easier to identify and handleable. Second, the longer a person remains in a group with a conforming opinion, the more it will reaccess his personal view to the new information (This is the reason ideology likes to divide persons from their friends and family or even turn them against their former circles). Third, the leaders themselves errornously begin to assume and search evidence that their brainwashing really turned all of their people (This is the reason dictatorships could not stop to meddle with election results to increase them up to 99% instead of a more plausible 60% which would still give them the power).
Stop your opponents from acting (Infighting, loss of social cohesion)
One reason which seems to be often neglected in the rise of dictatorships is the loss of social cohesion. In the years before the fatal year 1933 there were severe street fights between communists, nazis and civic parties, each having their own strongmen. Trump came to power for the very same reason: An intense dislike between the US left and the right which seems to have deepened to hatred. In this case the public is more open to extreme views; especially because the divided groups are living in the very own filter bubble of news which only confirm the own worldview and are not able to review their opinion in discussions with the conflicting group.
Left groups are known for such severe and pointless infighting and split-ups that this was parodied by the "Judean People's Front" against the "People's Front of Judea". The joke is so wonderful and sad because it hits exactly the spot; people are often more hostile to potential allies instead of the real ideological enemy.