Well, Well, Well...Do we have a serious inquisitor here?
For "understanding Nirguna Brahman(NPB)...". Let's stop there. Assume Nirguna Brahman cannot be fully understood. Period. OK. That leaves us with the question What aspects of the "Incomplete Nirguna Brahman" that you can bring into the "Saguna Brahman" or Domain of knowledge and reasoning and kind of "approximate" the Understanding by intellectual reasoning.
We are endowed with imagination and reasoning abilities. The Hypothesis mind.
Now, If you think Nirguna Brahman is everything that you can experience and "more" (I call it E++ :-)) then shouldn't you start looking for that "everywhere" that you experience?
For e.g. Books, Stackexchange etc. is one thing, Travelling around the world - if possible, doing your duties correctly wherever you are placed in whatever part of your life and gain appropriate experience, understanding, maintaining personal relationships, habits all then becomes important as well. Hinduism always prescribed becoming a Sage to inquire into the whole at the "last" - Golden year part of your life. "Aranyaka" is a forest. You are supposed to be introduced to the "Brihadaraynyaka" upanishad once you leave everything and go to the forest. But, we read it during coffee break! "Sathyam Vadha, Dharmam Charah..." etc. are Vedic statements required to be followed in all aspects of your life. These values, like, being your authentic self (Weezy :-)?), Getting rid of Ego, Super Humility, Truthfulness, Righteousness Adherence, Indriya control, Unbridled devotion, Performing your duties to the best of the abilities etc. ALL becomes important. Why? Because NPB "Knows and Measures you" - I mean the supreme consciousness aspect of NPB - In-and-Out. There is NO privacy. Since you are part of NPB. Neither can you run, Nor can you hide from your conscious mistakes/unconscious mistakes. You can console "Your" Self but not quite the Super-self. I mean it gets real Personal! So much, so that, you could go Mad. People HAVE gone Mad. This is NOT an easy journey. I can tell you why.
Nasadaya Sukta Talks about that. "In the beginning Darkness was Covered(or churned) in Darkness. The One rose due to their inherent "heat". That One breathed Windlessely". The First ones to realize NPB was both the Darkness in Heat. You could imagine how lonely you are being blind in darkness with nothing whatsoever. There was not even the Universe. That was the lower bound of all the "lows" of ALL sentience. You could relate that darkness to "your" personal darkness. Moments in your life that you were "beaten down" the "lows" in your life. When your journey towards the NPB knowledge becomes serious, so does the growth to your troubles in your personal life. Both the Primordial Darkness and their Cohorts(Shakthi, Yama and such...) tests you, validates you, checks if you are worthy or not etc. etc...The only goal MUST be to reach the understanding of NPB. Can you give up EVERYTHING Else? NO BINDINGS. No family etc..? "Can you leave behind your heart and cast away..:-)?". That Rule follows from the Primordial. That rule is applicable to You, Elements, Earth, Sun, Planets, Galaxies etc...Indra's soul, Even to both those Darkness themselves etc... Keno Upanishad Talks about Devas being tested by an Yaksha. Shiva kicks Yama once and protects Markandeya to crush his ego. Krishna, gets arrow-ed down by a hunter on the left foot. If he is Parabrahman, Why did he orchestrate the events in such a way? There may be reasons :-). If he used his mind, then that becomes a property and ipso-facto he becomes not Parabrahman and remains an Avatar. So assigning a name and calling Supreme Godhead or Krishna really doesn't make sense as far as NPB understanding goes. Let's look at Earth and Sun(assuming both are conscious) . What is dear to them? What is dear to Space? If they try to reach for more knowledge of NPB they will be put to test and they may have to let go of their "Heart" as well. Now you see the vast stretches of Love that could potentially span across space. The vast stretches of Love of Space of whatever that Space loves. Mmmmm....then is God Love? Is NPB Love ? Every body(or non-body) loves their own existence and sentience and not ready to give that up - Space included. That is their primary innate love. Next comes the love of other entities. Based on the entity that requires more knowledge, that entities disavowal of everything will be tested as well. Their post this-fact-realized disinterest and Not pre-if you know what I mean. The best for you to do is realize this and enjoy the realization in Silence. When you express outwardly what is dear to you, you and the dear are subject to the test :-). Now, you know why a Silent love is better than the Modern show-off, although it pleases the opposite. That love would be tested whenever you reach out to God or acquire more knowledge about Him. Now, sacrifice, that is very interesting. You give up something you love willingly. That has higher merit then. Many original sentient entities sacrificed willingly - like Usas - for some higher purpose, for a different way to realize Him as us- biological beings. Jesus was tested, sacrificed himself for higher understanding and did receive some key knowledge. Aghoris sacrifice social life for some siddhis, not really wanting anymore NPB knowledge. I do want to make a point that then Sacrifice shouldn't become a cliche. In earlier times, this was the case. Hanging upside down on trees, standing one-legged etc...etc...The intent MUST be original and the effort even more original. Dadichi was an original. Vishwamithra also was... but still tested on Indriya control. Now, you know why even the Great Rishis were afraid. Realizing this very fact, they were Trembled. They wanted to do the Yagna, Procreate etc. That is their heart, their love and their craving. You can't just leave behind everything! SO, No propitiation mantras to NPB. All Mantras are only to all lower level Demigods and at the most Saguna Brahman. You hold something dear to your heart and something comes along and breaks it down to pieces. Vishnu, Shiva and Brahma's abodes as well - Ganesha Purana. Vedas, Yagyas - if you hold them dear, comes along another religion not requiring that! These oscillations across the opposites the Yin-Yang, the Push-Pull, decides progress of Souls as a whole. We call it Karma. The Jewish religion Torah (part of NPB too...remember) talks about staying out of the way from the "Swaying Pendulum". Hinduism talks about "Being Silent, being inert etc. ". Many Rishis came out of Snake Mud pits around their body in early times after years of Tapas - Very cool ways, but as you can see, impossible today. Do something, there will be a three-fold karmic effect. A->B->C->A kind of thing..there are movies about this..the arrows not necessarily of the same length, time and direction :-).
If you are still interested, the quest is on your own. Since, NPB resides in you, He will guide you...I for my part could point you to some "interesting" reads...Remember, "Guru Sakshath ParaBrahman". Not many want to pursue this..bogged down in their daily routines...
To start with you could look at the conversation here...
"Think, So you become"...
Yad Bhaavaeti, Tad Bhavate.