There is a lot written on lucid dreaming. And I'm still pretty new to it but I thought I'd make some specific notes on it which parrallel hacking into a remote and foreign computer system

The general steps for performing a hack are
1. Reconnaissance
2. Scanning
3. Gaining access
4. Maintaining Access
5. Clearing Tracks
number 5 is not especially relivant for this but I'll discuss the others

Reconnaissance: Understainding dreams
The first step is to understand what it is you want to take control of. Unfortunitly dreams still are not extensivly understood by the scientific community. My understanding is that many parts of the brain become mostly inactive while keeping the autonomic system and the bare minimum congnitive functionality to allow the body to respond to threats. My armchair interpirtation is that as the brain sorts out memories and attemps to revuvinate it's physical structure and neurotrasmitter levels etc. (yeah a lack of REM sleep is REALLY bad for you and will kill you faster than starvation )The mind experiences some of this 'mental noise' the the active subconscious processes it in the same way it would with real experience. This becomes an interactive process of creating and perceiving. This may be proven to be false in the future that it's a good working knowledge for now. When you are targetting a system. You might not know the intrecesies but if you can develop a practical model, It's a start.

Scanning: Finding weaknesses
The first thing that stands out is that certain parts of the brain are 'asleep' when you are. This matters because, I'm not sure how obvious this is to the general public, but your sleeping mind is nothing like your wide awake mind. From a interllectual perspective, It's incredibly watered down. You are essentially mentally handicapped. In my experience, you can focus and summon acuity by what I assume is activating the logical parts of your brain but it makes the dream unstable and you can easily end up actually waking up.
Most of the things you rely on and even take for grantid in your waking life, you simply don't have access to when asleep. For instance, our memory and perception is pretty suggestive in dreams, we can accept and be convinced of nonsense. Object perminance simply doesn't exist. The mind takes on the role of generating as well as perceiving and it's not particularly good at it. Our mind has trouble even figuring out what we look like, often faces and hands look strange. Etc.

Lucid dreaming actually puts many of the limitations of the brain under a microscope. Your mind will say that you're driving through a forrest but when you stop to really 'look', you call those trees? Actually by now, your whole spacial awareness has gone and whatever that is in front of you becomes the subject of your next hallucination.

The second thing to note is that the subconscious is in control. This is the system with which you are going to get into your dream. When your dream puts you in a system, You generally act the way you would in your everyday life, you subconscious is reacting to the situation it finds itself in. You don't fly in your dreams because you don't believe you can in real life. This is the scaled down operating system your body uses when you're asleep and we're gonna hack it and boot strap our own.

Gaining access: Hack your dreams
our subconscious is pretty reliant on habbit. It's our autopilot that unintelligently performs sequences of actions for us.(if we had to 'think' about it each time we opened a jar or tied our shoe laces, we wouldn't get anything done) We are going introduce habbits that will 're program' our subconscious to do things without our concsious and rational intervention because that's what we're missing during sleep.
In a sense, we have probed our target and found out what operating system it uses. We know this system has a vulnerability where it will take user input ( habbitual actions ) without propper sanitization and will add it to it's current memory. So all we need to do is create a payload ( habbit ) that will will run shell code and give us more access to the machine ( activate dormant pars of the brain ) how are you liking this analogy?
We call these habbits reality tests. They test the physics of the world we occupy and provide an answer to whether or not we're dreaming. Such tests include:

trying to hold your nose with your mouth shut and breath: your real body is breathing fine

reading test: objecst have no permenance in the the dream world and are subject to change

flying: laws of physics need not apply

looking at your hands: the mind has a funny inability to fugure that out

can you add numbers: general logic is deficient when asleep

willing changes in your enviroment: your subconscious has total control over this and it can change

etc. Everyone is different, so freely experiement with these and others you can find. Some things havn't worked for me such has holding your breath and pushing your hand through objects. Others such as reading text has done the job beautifly but might be a more difficult to establish habbit.

one of my favorits is staring at text. You are reading this sentence right now. The sentence is made up of words, and those words, letters. When you read something in a dream, You skim over it and accept its meaning like in real life. Unlike real life however, if you stop and really look at the word, those letters probably wont spell what you read. Try staring and text, the first 2-3 letters in my experience were sufficient for me to dejuce that something was amiss, also the letters change before your eyes due to the non object perminance of your world.

I use this when possible with a digital LCD screen, like a watch of mobile. Text tends to be more willing to fluctuate when your looking at your mobile clock.
While experimenting with tests, I would stare at my watch and look away 3 times, If it stays the same, I'm not even mad, that's amazing.

Maintaining Access: keep yourself lucid
While you're lucid, try out your reality tests and see how they work for you. It's possible that the first time you become lucid is by chance so the the opportunity to see if you have a solid game plan. The first time I became lucid, My reality check involved my watch, From memory, I would check the time a few times to see if it changed, add the hours and minutes, what is 6+8? and see how fast the second had was moving. Analogue hands move but I think you could find more consist hacks, I couldn't be stuffed adding 2 single digit numbers together ( therefor it failed, make your tests stupidly easy ) and the second hand moved occasionally. I then closed my eyes and said 'lighter' and when I opened them the whole world was bright. Note that closing your eyes isn't something I read about, I just did it an expected it to work, and it did.

There are different levels of lucidity ranging from a fleeting acknoledgement of it being a dream to vivid imagery and self awareness. Keeping the hacking analogy going, There are different levels of access to a system. Keep escalating your privelages until you have complete control. The problem I have come across is as you become more concsious, you start to wake up ( Sysadmin calls the police? ) and your dream becomes unstable. I don't have a lot of experience with this but there are some things that are reccommended to stay in the dream, spinning around and rubbing your hands together. Rubbing your hands together is meant to stimulate you to keep you focused on your lucid experience. I would also reccomend, staying calm and not resisting what you're experiencing. Something else to do in general is regularly redo the reality tests to keep youself from slipping back into unconsciousness.