Learn from the theory and practice of the best
Fortunately, one of the most successful revolutionaries of all time, Mr. Vladimir Ilyich Ulyanov, maybe better known under his conspirative pseudonym Lenin, fancied himself an intellectual, had a severe case of graphomania, and left voluminous writings on the theory and practice of revolutions. He also actually led a most successful revolution.
According to Mr. Ulyanov, a successful revolution needs two things: (1) a revolutionary situation, and (2) a trained cadre of revolutionaries ready to assume power and lead the masses.
A revolutionary situation has three components:
"Those at the bottom don't want, and those at the tops cannot live in the old way."
"When it is impossible for the ruling classes to maintain their rule without any change; when there is a crisis, in one form or another, among the “upper classes”, a crisis in the policy of the ruling class, leading to a fissure through which the discontent and indignation of the oppressed classes burst forth."
"For a revolution to take place, it is usually insufficient for “the lower classes not to want” to live in the old way; it is also necessary that “the upper classes should be unable” to rule in the old way."
Acute dissatisfaction with the ruling class.
"When the suffering and want of the oppressed classes have grown more acute than usual".
Note the importance of acute. A revolutionary situation is fleeting; it is the task of the revolutionary leaders to seize it and to exploit it, because if the masses become habituated with their lot in life the revolutionary situation vanishes.
High political activity of the masses and readiness to revolutionary actions.
"When, as a consequence of the above causes, there is a considerable increase in the activity of the masses, who uncomplainingly allow themselves to be robbed in “peace time”, but, in turbulent times, are drawn both by all the circumstances of the crisis and by the “upper classes” themselves into independent historical action."
Lenin concludes that
"Without these objective changes, which are independent of the will, not only of individual groups and parties but even of individual classes, a revolution, as a general rule, is impossible."
All of the above are taken from the Wikipedia article on Revolutionary situation, which excerpts from the corresponding article in the one and only Great Soviet Encyclopedia and Lenin's Collapse of the Second International (link goes to Marxists.org, so you may want to exercise care).
But of course not all revolutionary situation eventuate into successful revolution. In order for a revolutionary situation to transform into a revolution there is an inescapable need for a revolutionary cadre of professional revolutionaries ready to recognize the situation and to take leadership, channeling the energy of the masses into a coherent sweeping movement.
There must be a coherent ideology shared by the revolutionary cadre, and sufficiently disseminated so that the masses will at least recognize it, even if they don't initially share it.
There must be a pre-existing well structured and well disciplined organization, comprising both thinkers such a Lenin, and doers such as Trotsky or Stalin.
At least some of the revolutionary cadre must have had successful practical experience at leading men. For example, before the Great October Socialist Revolution which Took Place in November, Mr. Joseph Vissarionovich Jughashvili, better known as Stalin, led an organized crime gang based in Baku, the Outfit, which engaged in "armed robberies, racketeering, assassinations, arms procurement" etc. (short summary from Wikipedia.); and Mikhail Frunze organized disruptive strikes of industrial workers.
And then, once the revolutionary situation is recognized, the revolutionary cadre assumes power, that is, they pretend to be the lawful government and start issuing orders in the full expectation that their thugs will enforce them. More often than not, their effective power will be limited to a small part of the territory of the state, with other parts of the territory controlled by other parties; a civil war is the most common outcome.
Immediately after assuming power and asserting control over some territory, the revolutionary cadre must unleash a barrage of agitprop on the masses, to nourish and grow the seed of the revolution and transform it into the new way of life. For this purpose, some of the leading artists (and, nowadays, influencers) of the country must be coopted and placed in the service of the revolution.
And then, of course, they must begin to actually run the state...
OK, but what about the army?
There are four possibilities:
The army can be counted on to remain aloof and not interfere with the political transformation; the best example is the French Revolution, where the bulk of the army simply stayed in their camps and did nothing, waiting to see who comes on top, and then continued to obey the orders of the civilian authorities, whoever they were.
Or, the army, in whole or in part, is coopted into the revolution. The perfect examples are the Stuart Restoration and the English Glorious Revolution of 1688.
Or, the army so thoroughly disorganized that it doesn't matter what it does. This was the case in the Great October Socialist Revolution in Russia; the army had been so thoroughly beaten by the Germans that it had lost all cohesion and fighting capability.
Or, there is basically no army around, as was the case of the successful armed rebellion of the 13 American colonies against their legitimate King. When the British Crown got around to sending an army, the deed had been done and the revolutionaries were the effective government of the colonies. (Yes, the Crown did have a small number of men in the Colonies, but they were grossly outnumbered by the rebels.)
If neither of those four conditions is met, this means that the revolutionary situation is not mature enough.
Bonus
I cannot resist including a handful of examples of early Bolshevik and Soviet visual agitprop...

Beat the Whites with the Red Wedge, by El Lissitzky. (The Whites were the opponents of the Red Bolsheviks in the Russian Civil War. For obvious propaganda reasons, the differences between them were ignored. Who was not Red was an enemy White, and that was that.)
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Lilya Brik shouting Books! In all branches of knowledge! Work by Alexander Rodchenko for Lengiz (= Leningrad State Publishing House).

To have more, we must produce more. To produce more, we must know more. Work by Alexander Zelensky (sorry, in Russian, as he is unknown to the English Wikipedia).

Literacy is the path to Communism. Anonymous work for the Likbez (= Elimination of illiteracy) campaign. The scripture held by the rider on the red Pegasus reads, of course, Workers of the world, unite!

The triumph of Christianity. Work by Dmitry Moor.

Either death to capital, or death under the heel of capital! Work by Viktor Deni, who is also the author of the well-known poster showing comrade Lenin sweeping the scum off the face of the Earth.

Damn scarecrow! Work by the above-mentioned Dmitry Moor. The unraveled scarecrow is labeled Antanta, which is Russian for the Entente, the Allies in WW1; this is what the Red Bolsheviks called the foreign intervention in the Civil War.

The road to worldwide October. The paper on the table read "crisis". The upright panel reads "Hoover plan". The Red Bolshevik does not read. Work by Viktor Deni.

The world is standing on a volcano... and then what happens when the caged proletarian escapes. Work by Vladimir Mayakovsky for the very effective ROSTA Windows. (Yes, it's the same Mayakovsky as the poet.) (ROSTA became TASS in 1925. It still engages in propaganda.)
¡Viva la Revolución!