“As a young child, the Rebbe [Rebbe Nachman of Breslav] wanted to literally fulfill the verse ‘I have set G-d before me constantly.’  He continually tried to depict G-d’s ineffable Name  before his eyes…” 
“The main way the Rebbe attained what he did was simply through prayer and supplication before G-d. He was very consistent in this. He would beg and plead in every way possible, asking that G-d have mercy and make him worthy of true devotion and closeness.
The thing that helped him most was his prayers in the language he usually spoke, which was Yiddish. He would find a secluded place and set it aside to express his thoughts to G-d.
…He kept this up constantly, spending days and years in such prayer.” 
It seems to me that there’s a connection between Rebbe Nachman’s early application of the psalm-verse, and his later practice of private, personal prayer (“התבודדות/hisbodedus/hitbodedut,” which didn’t replace formal “Tefilah”). They’re not two separate devotional or spiritual practices. Rather, I get the intuitional feeling that by constantly setting G-d’s Name before himself, Rebbe Nachman came to some degree of conviction — even as a child — that G-d is always present to him; he’s always in G-d’s Presence. One might realize this “intellectually,” yet without it being a heart-felt conviction. Rebbe Nachman seems to have early felt it in his heart. From there, it’s inevitable to ask: How do I open to, grow closer to G-d? How do I interact with this Presence from which I’m never — and can never be — absent or separate?
Rebbe Nachman also seems to have believed — as we’re all taught to believe — that everything depends on G-d. “Not by power, or by might, but by My Spirit…”  Although he had to make efforts (rather than passively expecting results), Rebbe Nachman constantly, consistently placed the outcomes in G-d’s Hand. He didn’t do this by silent assent. He did it by private prayer — but prayer which he spoke aloud in a secluded place.
By “…set it aside…,” the text also seems to suggest that once he chose a place, the Rebbe did nothing else there but speak aloud to G-d. No learning, no picnic, no enjoyment of nature for its own sake. It was a spot that had no other association for the Rebbe than as a place to speak to G-d. We, too, might learn from this to set aside a place that has no other association or use for us than as a place where we meet with G-d.
Thus, in doing hitbodedut/private prayer, the Rebbe was simultaneously also “placing G-d’s Name” before himself.
This week, I happened to have the great opportunity to hear Rabbi Shalom Arush speak. Rabbi Arush is at this time the pre-eminent Breslav teacher of hitbodedut. He’s spreading it outside of the Breslav community, into the Orthodox community and beyond: It was mentioned that he’d even spoken to large Christian audiences (in South Africa, if I remember correctly). Rabbi Arush can be seen modeling how to do hitbodedut at: http://www.youtube.com/watch?v=8IKoxPYj06Q.
Rabbi Arush mentioned that Rebbe Nachman didn’t invent hitbodedut. This is true. But I think that one of the Rebbe’s innovations was to recommend — perhaps insist — that it be done regularly, daily, consistently, rather than occasionally or “as needed.” Rabbi Arush continues the Rebbe’s teaching in this regard, emphatically encouraging us all to spend one hour every day talking to G-d, placing every aspect of our lives in G-d’s Hand. I don’t think that he’s well-known yet in Reform, Conservative and other extra-Orthodox Jewish communities, but I fully expect that he will be. Eventually, I see all Jews incorporating hitbodedut into their daily lives, whatever else their observance.
I also think that doing it in a secluded, quiet place — while not unknown in itself — gave the Rebbe’s direction further uniqueness, specificity and definition as a practice. G-d is everywhere. One can speak to G-d anywhere — on subway trains, on buses, in cars (not necessarily while driving), in markets, etc. But the Rebbe urged us to find a quiet, secluded place where we can talk to G-d without distraction and without self-consciousness. He might also have intended that it be the same place as often as possible, and that we do nothing in that place other than talk to G-d, but I’m not sure that he was ever explicit about this.
Finally, the Rebbe’s emphasis that our private, personal prayer can — should — be done in our own conversational language, whatever that might be, is again an innovation. Elsewhere in Judaism, formal prayers are given primary importance. Traditionally, Jews formally pray in Hebrew. Hebrew is called “loshen kodesh” — the holy tongue/language — because of its use in prayer, Torah and Talmud. For that reason, in the early Zionist era, there was much opposition to making Hebrew a modern spoken language until Eliezer ben Yehudah’s work more or less settled the issue. Rabbi Arush, following Rebbe Nachman and without demeaning formal prayer, affectionately and humorously reproached those who pray formal prayers so quickly that the words can’t even be understood. He said that in Heaven, they look at each other and ask, “What did that person just say?” Prayer, he said, should be a vessel for G-d’s expression of goodness in our lives. This is best accomplished by praying in our own words, in our own language.
Rabbi Arush teaches that we should do hitbodedut for one hour each day. Did Rebbe Nachman specify an exact amount of time? I don’t know. Nor, I think, should we be strict “clock watchers.” Our conversation with G-d shouldn’t be so short that it’s merely perfunctory. But we shouldn’t count the minutes, either. I think we have to look honestly into our own hearts, as Rebbe Nachman always did. “Did I pour out my heart to G-d as fully as I can today?” “Did I tell G-d everything that I’m thinking and feeling?” “Did I place all my needs and concerns in G-d’s Hands?” And so on. The essential thing I see Rebbe Nachman saying is to do it every day. 
In his book, “In Forest Fields,” Rabbi Arush talks about the confession and t’shuvah that should accompany prayer. While I don’t — can’t — disagree with him, I’d suggest to anyone starting the practice of hitbodedut: Begin as simply as possible.
Just talk to G-d.
Is G-d inside of you? Outside of you? Near to you? Far away from you?
None of this need matter. That G-d hears every word you say, knows every thought and feeling in your mind and heart; that G-d can do absolutely anything, loves you and wants to give you all good — dayyenu.
Maybe you’re not even certain of that?
Then, you could start talking to G-d, thinking: “G-d might be hearing every word I say; might know every thought and feeling of my mind and heart. G-d might be able to do absolutely anything. G-d might be willing to do absolutely anything for my good.”
Place everything about your life in G-d’s Hands. Let certainty come in its own time.
If — as sometimes happens to me — your problems begin to occupy too much of your attention, or even upset you, when you’re talking with G-d, learn to then talk to G-d about G-d. Say what amazes you about G-d; tell G-d the things that make you love G-d. Repeat those, expand on those, until your mind is calm and happy. Then, bring in your personal concerns gently; without insistence or self-will.
Rabbi Arush said: G-d already loves you more than even the most loving parent loves their child.
Dwell on that Love and you dwell in G-d.
 Tehillim/Psalm 16:8
 The four letters Yud-Key-Vav-Key.
When writing the psalm, King David didn’t necessarily mean that he depicted the letters per se as Rebbe Nachman did, or contemplated their Kabbalistic significance (as the Besht seems to have been doing when quoting the same verse in the Tzva’at Rivash). Still, these later practices show contemplative applications of the verse.
 Rabbi Nathan of Nemirov; Rabbi Nachman’s Wisdom; Rabbi Aryeh Kaplan, trans.; Rabbi Zevi Aryeh Rosenfeld, ed.; (seems to have originally been self-published, as my copy lists no publisher or copyright date; later editions might do so); p. 5
 ibid., p. 10
 Zacharyahu/Zechariah 4:6; this verse also appears in the haftarah for Shabbat Miketz during Hanukkah
 Rabbi Chaim Kramer writes:
“Practically speaking, it takes an hour or so to fully reach the stage where a person can speak to G-d about all the things that are on his mind and in his heart. The topics to address can include one’s health and that of one’s family, livelihood, emotional well-being and, of course…one’s spiritual needs and wants. For most beginners, however, even those with previous experience in meditation, a full hour might not be realistic. Therefore, when first starting out in this devotion a person might make do with a ten or fifteen minute regimen and gradually build up his time, until he reaches that hour of hitbodedut which the Rebbe recommends…”