The day begins with Modeh Ani ("I acknowledge before You, living and eternal King, that You restored my soul to me; great is Your faithfulness"). This is said before the morning washing of the hands, even while the hands are ritually impure (and all other prayers cannot be said). The deeper reason for this is that all the impurities in the world do not defile a Jew's "I acknowledge" before G-d; he might lack one thing or another, but his Modeh Ani remains intact.
The Lubavitcher Rebbe (Hayom Yom for Shevat 11)
Dawn (Alot Hashachar)
Earliest Tallit and Tefillin (Misheyakir)
Sunrise (Hanetz Hachamah)
Midday (Chatzot Hayom)
Nightfall (Tzeit Hakochavim)