The 'amida or Shemona-Esre --also called by our Rabbis "Tefila"-- is the most important prayer. It is said every day, three times a day, morning, afternoon, and evening. When we pray the 'amida we are talking directly to God. There is nothing more significant for a human being that communicating with his or her Creator.
FOCUS: We should not start praying the 'amida unprepared or unfocused. The 'amida requires 'kobed rosh', a serious effort of concentration. In preparation for the 'amida we must visualize and internalize that we are standing in front of the King of Kings. Literally, 'amida means: "The prayer which is said while standing". In the Jewish protocol a servant stands in front of his King, with his feet together and keeping his head a little down as a sign of humility and submission to the will of the Monarch.
POSTURE: Strictly speaking, the posture we adopt in the 'amida conveys: "I'm standing at Your service, waiting for Your command". For this reason, many would recite the 'amida with their hands together, on the chest, the right hand holding the left closed fist.
ARTICULATION: The 'amida should be said articulating the words. Articulation -among other things- facilitates a better concentration (=kavana). We should say the 'amida whispering it to ourselves (lahash). So low no one else could hear our voice, and loud enough we could hear our own whispering.
KAVANA: When saying the 'amida, we should think and then delve into the meaning of every word. This mental exercise is called Kavana: consciousness / alertness. Distractions or even having a blank mind is not accepted. If we get distracted during the 'amida, particularly while saying the first berakha, Magen Abraham, we should say the 'amida again, provided we are sure that this time we will be able to concentrate properly.