Following up on Isaac's question seeking experience-based advice to improve his prayer:, I am seeking something a bit different. I remember reading some advice on the subject given (I think) by Rav Schach, zt'l, that one should from time to time use a different siddur in order to force himself to go through the siddur word for word and concentrate on what he is reading. Can someone point me to published suggestions by other gedolim?
Rabbi Weinberger of Aish Kodesh http://www.ravmosheweinberger.com/, speaks at length quite often on the topic of prayer. Most recently, I have been re-listening to his shiurim on Bilvavi Mishkan Evenah. It has reminded me that kavanah does not simply start with the actual act of prayer, it is a life-long quest to continually remind ourselves that Yesh Bo're Olam, there is a Creator of the world, yitbarakh shemo.
Over the past few days, since I started reviewing Rav Weinberger's shiurim, I have found it quite helpful to remind myself during prayer that every single moment is an act of creation and Hashem Yitbarakh is continually involved with every single moment of existence. Literally, that very moment at which I said the Shema, Hashem Yitbarakh was creating my lungs, lips and brain such that I could utter the words in this physical world. As the Ba'al HaTanya reminds us, "Hashem is very near to you."
In addition, I once heard by the Gerrer Hasidim a common meditation in prayer was to picture oneself standing before the throne of Hashem Yitbarakh while praying. You literally try to picture yourself standing at the the feet of a massive, universe encompassing throne. You continually remind yourself that you are in fact always standing before Hashem Yitbarakh.
Rebbe Nachman of Breslov has an enormous amount to say about this topic. Many of the paragraphs in the chapter on prayer in Likutei Eitzos relate to concentration in prayer:
Some further selections, from Sichos HaRan and other sources, are collected here (The Essential Rabbi Nachman, edited by R' Avraham Greenbaum):
To summarize briefly, here are some of his pieces of advice:
1) focus on the simple meaning of the words
2) make sure to say the words with sincerity and truth
3) simply push irrelevant thoughts aside, or ignore them
4) try concentrating on a particular part of the service, and eventually exapand the portions of the service which you're able to daven with kavanah (Sichos Haran #75)
5) exercise great determination and firmness in pushing away irrelevant thoughts
6) make sure to pray audibly and to listen carefully to the sound of your voice
7) give charity for causes in the land of Israel
8) study the legal codes daily (see paragraph 55 in Lukutei Eitzos)
9) be prepared to sacrifice yourself for the sanctification of G-d's name
10) search for good points within yourself so you will be happy
11) force yourself to concentrate (paragraph 88, 90)
12) offer hospitality to a Torah scholar (paragraph 67)
13) say the words simply as if you were a little child (paragraph 92)
14) get yourself in a happy mood before you pray (Sichos HaRan #75)
15) pray with a happy tune (Id.)
Rabbienu Avarohom ban HaRaMbaM HahHosid in his Hamaspig laOvdei HaShem says that the foundation of Judaism in our times and obviously in his is Taffilo. Taffilo is the Ovodoh of our times therefore to have a stable foundation in Judaism one needs to start with the proper Taffilo. What is proper Taffilo? It is as if a person is standing infront of a king and he is begging him for what he needs (sustenance). One should come to the king with proper clothing which is clean and clean body, clean environment, nothing should be distracting him in the area, clean thoughts,and have a clean heart(Mishnei Toroh chpt4 holochoh 1 by Rabbeinu Avarohom's father RaMbaM). Once these things have been taken care of before time for prayer, during prayer one must be careful to be standing not sitting or leaning on things for support for the only support a person needs is HaShem, lest he is sick or old and he can't pray without sitting or leaning on something, he should be facing towards the Beith HaMeegdosh, he should prepare his body for meaning he should have his feet together and his arms should be on top of his stomache at around the heart level and he should have the right hand over the left, and his eyes should be looking downwards as if he is a slave and unworthy of looking at the holiness of the king, but at the same time he should keep his heart in the heights of heaven. He should adjust his clothing as to not look like disrespectful before the king, he should be standing in a proper place facing a wall, and the wall has windows he should open them, he should also have a proper tone in his voice as if he is singing his praises and his needs to the king, and the last two are keedoh waheeshtahHawoyoh(chpt5 holochoh 1). Rabbienu Avarohom in his Hamaspig goes into depth regarding all these subjects. What he says is that the navee'eem and common folk did not do keedoh waheeshtahHawoyoh(naphiloth apoyeem) the way we do it today. He brings proof from T.N.K and the Gamoroh, that real keedoh waheeshtahHawoyoh(naphiloth apoyim) is by going on your knees, beerkayeem al apoyeem, similar to what the muslims do. He says it is of no concern that muslims do birkayeem al apoyeem because they took the meenhogeem from OUR navee'eem and we took the arabian meenhogeem as the posuk says " אַף חֹבֵב עַמִּים, כָּל-קְדֹשָׁיו בְּיָדֶךָ; וְהֵם תֻּכּוּ לְרַגְלֶךָ, יִשָּׂא מִדַּבְּרֹתֶיךָ." Yiso Meedabrothacho, meaning they took our meenhogeem, yet we took their meenhogeem with regards to our woman dressing up as their women using a garment called a bageer. Therefore, the meenhogeem of the goyeem are our own meenhogeem which we dropped and which we should reclaim. Therefore, doing proper naphiloth apoyim is the best way to attach oneself to HaShem, like a slave/avad infront of a king/malach. In Yalkut Shimoni(http://www.tsel.org/torah/yalkutsh/shmuel.html#A1277), it says that the purpose of the Beith HaMeegdosh was for heeshtahHawoyoh, and the purpose of the next Beith HaMeegdosh will be the same, without proper tefillo, the Beith HaMeedgdosh won't happen.
I hope this helps with proper tafillo. HasSlocho Rabo.
Rambam, in Mishneh Torah, says the following:
"One should clear his mind from all thoughts and envision himself as standing before the Divine Presence. Therefore, one must sit a short while before praying in order to focus his attention and then pray in a pleasant and supplicatory fashion.
One should not pray as one carrying a burden who throws it off and walks away. Therefore, one must sit a short while after praying, and then withdraw.
The pious ones of the previous generations would wait an hour before praying and an hour after praying. They would [also] extend their prayers for an hour."
By "sitting," Rambam presumably means meditating, because the purpose of the sitting is to "clear his mind from all thoughts and envision himself as standing before the Divine Presence." So Rambam seems to be saying that one should meditate on G-d for a while, by visualizing the Shechinah and clearing one's mind of other thoughts, before beginning davening to ensure one davens with kavanah.
As for other gedolim, I believe the approach of Chabad, as described by the Alter Rebbe in the Tanya, towards achieving kavanah is to meditate on the greatness of G-d before davening. This leads to a great love and awe for G-d, and motivates the meditator to serve Him with enthusiasm and holy intentions.