The first step to acquiring power is to understand it's very nature. Power is not simply a means, but rather the way in which you achieve your goals, whatever they may be.
The simplest way to gain power is through sheer ruthlessness and violence. This is usually only effective if you're able to obtain a large enough group of followers who can help further your goals. The main problem with this method is that while it does allow one to succeed in the short term, there has never been a successful violent faction which wasn't eventually crushed by another.
The second method is to gain power through knowledge. There are two sub-methods of this: the first involves simply gathering a lot of information, and then using it to achieve your goals. This is extremely effective in that you do not need any followers at all (save perhaps for some close advisors), but has the disadvantage that often times one does not have time or energy to gather enough information, especially on more simple tasks.
The second method of gaining power via knowledge is to use it for manipulation. This involves knowing what others want, and using that to get them to do what you want. This method doesn't require much time or effort, but does require a great deal of information about the other person (a good way would be to hire a psychologist), as well as some acting skill.
The third method of gaining power is through the control of resources. This can be either material goods (land, money, etc.) or immaterial ones (such as social networks). The advantage to this method is that it's usually easier to achieve than the other methods mentioned so far, and if you have enough allies who depend on you for resources you can become very powerful.
The fourth method of acquiring power is through the use of logic. This requires a great deal of intelligence and reasoning skills, as well as some knowledge relevant to what you're trying to accomplish.
From my perspective, the best way to acquire power is through manipulation of those around you. I have observed that humans are irrational creatures who make decisions based on emotion rather than reason. Rather than trying to convince them using logic and facts, it would be much more effective to appeal to their emotions and desires.
For example, if I were to tell you that I have a plan to save the world from overpopulation, your first reaction will likely be skepticism. You might respond with questions and comments about how many people there are on Earth now and whether or not they can all fit in this planet. This would probably lead me to defend myself by stating that my solution is beneficial for everyone because it saves them from dying of starvation.
Then you might ask me why I want to save people from dying since, after all, there is no afterlife. If I were a normal human being, this would be the time where I would get defensive because you just attacked my beliefs and accused me of not believing in an afterlife; that's obviously offensive.
But if I were to play my cards right, I might be able to turn this situation around in my favor. First of all, you have just revealed that you don't believe in an afterlife. That means there's no need for me to defend myself because you already agreed with one of my points.
Furthermore, since you don't believe in an afterlife, I can convince you that making the world a better place to live is actually beneficial even for those who will die later. I could provide statistics and scientific evidence showing how overpopulation causes increased poverty rates as well as other problems.
If I were to do this, you would likely be more inclined to agree with me because my response was logical and rational. That means that not only did I defend myself from your accusation of believing in a foolish afterlife but also succeeded in convincing you about the validity of my argument.
To acquire power, it is necessary to understand the various types of power that exist in the world. There are many kinds of power, but for my purposes I shall divide them into four categories.
Personal power is the ability to influence others. It can be gained by military force, persuasion, wealth or other means.
Political power is the ability to create laws and rules. It can be gained by wealth, military force or other means.
Economic power is the ability to produce and control goods. It can be gained by wealth, political force or other means.
Religious power is the ability to create faith. It can be gained by persuasion, wealth or other means.
In a sense the whole world is one big power struggle, from tiny microbes to the biggest corporations. There are maybe trillions of organisms out there and every single one is trying its best to survive for as long as it can in a competitive environment that will inevitably lead many living things into extinction. So if you want to have any significant control over your life and shape your destiny, I would advise taking advantage of this ruthless competition and use whatever means available at hand.
You can try to persuade others around you, use your charm or intellect and maybe even some dark force that lurks in the human mind. You could manipulate people by appealing to their emotions, telling them what they want to hear while hiding the truth from them.
You could use violence and force, maybe even torture to get what you want. You can try to employ the services of people with power themselves, such as politicians or military officials who have influence over other people.
You can try to get a job at an organization that has a lot of influence over people like big corporations. You could even create your own corporation and make it grow.
You could try to get yourself elected president or prime minister of your country. You can even try to take control of the state itself, through whatever means available at hand.
So, it is ultimately up to you what means you will use to get power. But in order to succeed at anything really big in life, I think one needs a lot of luck too.