How do you start making sense of things?
You have been doing it since you were born. Our brains are engineered to make sense of things, even when there is no sense in them. Consider a clock. It truly sounds tic-tic-tic, but our brains will make us hear tic-tac-tic-tac instead. Our brains are patterning machines and will impose pattern in whatever is available.
Of course you want to make good sense of things. How do you that? Through experience. How do you acquire experience. By making bad sense of things!
So, again, observe and learn from your mistakes.
Doesn't other people's opinion matter?
No, they don´t.
Opinions are like arseholes. Everyone has one.

How can I live out my life without being affected by other people's opinions?
It is surprisingly easy. Just pay no attention to them.
Far more difficult is to live your life without being affected by other people´s actions.
Language is a model for sensory experience, just like a map is a model for a
territory. The usefulness of a model is dependent on how well it represents what it is modeling. So we want our maps to be accurate to be of any use. Likewise we want language to be free of semantic mal-formations.
The implicit statement that other people´s opinions affect your life is a semantic mal-formation, a good example of bad language modeling. In reality nothing can affect you, only you can choose to be affected.
Hence, Johnny cannot annoy me, since annoyance is an inner state and no one has the power to cause inner states on me. I am the only one with this power. A better linguistic model for the experience would be: Johnny does something and I chose to react by getting annoyed.
Of course, once you phrase it like that you realize you have myriad choices in how you will react. With a bad model you have no choice, you become increasingly limited and you don´t like it a bit. It is a big temptation to blame Johnny. However the true reason for the experience of limitation is not to be found in Johnny´s opinions (or even actions) but rather in the peculiar way I have used language to model the situation and describe it to myself.
What if I am a walking mistake, and I am trying to do the impossible? My study and practice has led me again and again to this conclusion. How do I change that?
Let me reassure you.
Yes, you are a walking mistake.
Yes, you are trying to do the impossible.
And no, you cannot change that.
This is called the human condition and it holds true for every and each human being.
No one knows anything.
No one can do anything right.
Yes, whatever your aim you will fail miserably.
But…
Even though you will most certainly fail, you will get pretty close to success. Maddeningly so. Therefore pay close attention to the next sentence, for everything hinges on it.
Always establish the highest aim you can possibly think of. Always go after the most impossible dream. Surely you will fail to achieve it, but you will get pretty close to it. (Personally, I like perfection to be my aim)
Choose a mediocre aim, a low dream you may believe is in your power to achieve, and guess what? You will fail miserably. But what you will get is a far inferior result than what you would get if you had aimed high and failed high as well.
If you now direct your practice and study according to this new guideline, your study and practice will convince you of the correctness of this new conclusion.
Do I love bernhard? I do I do I do I do.
(Looks like I have fallen into a delusion despite the warning.)
Lucky him!
How do I gain levels of being/ experience? (Aside from simply living.)
Mostly by voluntary suffering. If you are hungry and have no food, this is involuntary suffering, since there is nothing you can do about it but go hungry. If you decide to fast for two weeks even though there is plenty of food in the fridge, this is voluntary suffering. The friction between “yes let us eat, I am starving” and “no, I am fasting for two weeks” will generate large amounts of inner heat with which you will be able to forge a new level of being. Observe your inner state as you go through this struggle. Of course fasting is just an example. Piano practice can also be used for this purpose. Once you get the hang of voluntary suffering, you can use any suffering life throws at you (and there is always plenty available) and embrace it voluntarily, and in this way use it to further your level of being. But this is difficult. You will need a high level of being to accomplish it.
Also, consider that everything in the universe is neutral. It is we who either like or dislike it and label it good or evil according to our personal likes and dislikes. So, choose the thing you most dislike. This is what you should do next. Once you start liking it, go to the next thing you dislike doing. Until there is nothing left that you dislike. (you will probably die before accomplishing this task).
Likes and dislikes will then become a matter of choice. This in itself is one of the indications of a high level of being.
Thank you for the wishes, Sir Bernhard.
You are most welcome, Lady db05.

Best wishes,
Bernhard