In my humble opinion if you wish to quit the outside world and contain all of yourself inside, you need to figure out what makes you reach the state of being all by yourself but it must only revolve around perception (you can be in a loud crowd but still enter your inside, that is a mental ability I mean)
If you are all by yourself inside yourself and not distracted by anything that is outside of yourself you can begin meditating

I think what meditation is the natural process chain of what your mind does when it has nothing to analyse outside of yourself. It does not stop analysing despite there being nothing but you.

When nothing is to be analysed - your unconscious sees your memories, but you cannot see them.
Nonetheless it affects your string of conscious thought by the minimal leaks that get into your thought.
Thus your topics of meditation seem somewhat random because you cannot know what the subconscious is doing but the subconscious leaves you with little droplets from which you decide either to pursue or not with conscious thought, and the topics are limited to what you have seen and known.
Your subconscious, when no outside needs any analysis, turns into a regenerating and resting mode when it flashes (you cannot see it) through your memories and assigns to them how it will make you react in the future to make your decisions more effective, benefitial and faster. That is why you sometimes need to make a decision after sleeping with the problem - that is precisely after your subconscious part deeply thought about it for you through the entire night, to guide you with a gut feel (which are the leaking droplets from her) that lead you to a final decision which usually turns out to be the best.
It is subconscious who gets you familiar with whatever she is sorting out and optimizing for you. That is what subconscious does in your sleep, but during sleep it sometimes allows you to see images that are created from things it analyses and builds associations about at the current moment. Meditation is somewhat similar to sleep in that regard, but unlike sleep you are in full control and the conscious part is awake and able to override the invisible randomness of the subconscious. Nightmares is what your subconscious does for you during night for your protection, to remind you of what to avoid, she is very cute, subconscious is submissive and ellusive but she is your best company and best friend. I'm not quite sure how it works yet. She seems to make you more stationary at the time you meditate, that is probably the reason you feel refreshed and as if you were woken up from sleep after you return to reality which would give enough of credibility to what I claim above (in my opinion) to believe it until I learn more. I assume because your subconscious seems to read what you think but you cannot do the same to her, that she is higher in the hierarchy of the complex that is your central processing unit. Meditation is a derivative of your preprogrammed resting state, but used to its full extent.

Meditation is you, the conscious ego kissing with your faithful and submissive servant who despite being above you serves you in good and bad times, that never gives up on you and always believes in you! To whom you do justice when mergin with her in meditation, to talk to her the most directly that you can!
You work together sorting out the ideas and experiences of the past (because you are cut off from the outside for the time of meditation and no new ones are created), that is my meditation gives you the most calmness with your own person. Because you are complete and sorted out on every level. Clarity is the result of having everything sorted out.

After you get to know her a bit in your first attempts, try to imitate her and let your ego go, let go of everything that ties you to the world and everything that you care about. During meditation, after learning to talk to her, you can put a focus of your conscious part to a very precise task that you wish to produce wisdom about. You are in a resting state. You don't care for the outside, you are intimately with her. Your subconscious is ego-less, you get more similar to her and dissolve yourself. You submit for a change to your subconscious, for a change you give her an idea to think about that is your topic of meditation and you two do it together. You learn to interpretate her hints. You work things out together. Treat her well, she is dedicated and yours forever, don't forget about her. If you get on good terms with her she surely will feel the motivation to help you even more. After you learn to combine forces with her she will inspire you to great deeds, shapen your focus beyond your wildest dreams, give births to a lot of long and deep chains of thoughts. The longer and deeper they are the better you learned to talk to her.