Taking Three Steps Back
Before Shmoneh Esrei
- It’s proper to take three steps forward before Shmoneh Esrei to show that one is going to do an obligatory mitzvah. The halacha doesn’t require taking three steps back, but the minhag haOlam is to take three steps back in order to take three steps forward. 
- If taking 3 steps back in order to take 3 steps back involves waling into the 4 amot of someone Davening, don’t take these steps back at all and just start Shmoneh Esrei. 
- Some have the custom of saying ki shem Hashem ekra havu godel lelokeinu before the shmoneh esrei of mincha or Mussaf. If one forgot it and has already begun Hashem sfatai he does not go back. 
After Shmoneh Esrei
- After Shemonei Esrei, one should make take three steps backwards while bowing like a servant parting from his master. If one didn't do so, it is as if one didn't pray.
- There’s an absolute obligation to take 3 steps back after Shmoneh Esrei and wait there until the Sheliach Tzibbur gets to Kedusha or at least starts Chazarat HaShas.  An individual who finishes Shmoneh Esrei should take take three steps back anf wait there the time it takes for the שליח Tzibbur to reach Kedusha or in extenuating circumstances at least the time it takes to walk 4 amot (3 seconds or so). If one doesn’t wait after taking the 3 steps back it appears that one didn’t take the 3 steps back really in order to depart from Hashem respectfully. 
- One should start with left leg, stepping exactly behind the line of the end of the right leg, and then the same with right leg. By the third step one should align both legs into the same line.
- It’s proper to take three steps forward only after waiting the proper time (subsequent to taking three steps back). 
- Rama 95:1, Mishna Brurah 95:3, Piskei Teshuvot 95:3
- Halichot Shlomo 8:33, Piskei Teshuvot 95:5
- Sefer Meorer Yeshainim 24, Piskei Tshuvos 111:2
- Gemara Yoma 53b, Tur 123:1, Kaf HaChaim 123:1
- Shulchan Aruch O.C. 123:2
- Mishna Brurah 123:11
- Shulchan Aruch O.C. 123:3
- Shulchan Aruch O.C. 123:2, Mishna Brurah 123:8 writes that one should rush taking these the steps forward because in doing so one will loose the actual law regarding waiting in the place one took three steps back.