Four very old minhagim are based on events described in Parshas Lech Lecha. When Avraham Avinu expressed his concern that he was already so old that probably will not have any children of his own, Hakdosh Baruch Hu instructs him to go outside of his tent under the night star-filled sky. Can you possibly count all of the starts? So too will you have so many descendants that it will be impossible to count them all. For many generations it was the custom for a younger girl to get married outside, to invoke the Divine blessing of having many children. When a woman getting married was older, and the couple was not expecting to have any children, the wedding ceremony would be done indoors. Some trace this practice back to the days of the Talmud (see B'ikvei Hatzhon, p. 266)
When Avraham Avinu performed the mitzvah of bris milah, the Torah tells us that Hashem gave him the entire land of Eretz Yisroel. An individual person or even a family certainly doesn't need an entire land! Obviously Avraham would be the founding father of an entire nation, and the land will belong to that nation. Rav Yaakov Emden claims that our common custom of giving a gift to the baalei simcha upon the occasion of the celebration of a bris derives from this biblical narrative. We follow the lead of Hakdosh Baruch Hu who also gave this major gift (of all of Eretz Yisroel) upon the occasion of the very first bris.
In the sefer Matteh Moshe (by Rav Moshe Matt, student of Maharshal) it is recorded that the custom is to wait to name the baby until the bris. This is reminiscent of that fact that Avram was given a new name (Avraham) at the time of his bris. In truth, the case of Avraham is totally different from ours. Avraham's bris served the function of geirus (conversion). His neshama and personality were undergoing a major change. To use the Talmudic metaphor, "geir shenesgayer k'kattan she'nolad dami - a non-Jew who converts is likened unto a newly born baby". In this case it made sense to give him a new name. The new name indicated that he would serve the role of "founding father" of the Jewish people. This really does not apply in the instance of a simple bris celebration. Nevertheless, the custom is to reminisce over the giving of the name "Avraham" at the occasion of his bris.
The Talmud records an ancient custom that when bathing, dressing, and putting on shoes, one always takes care of the right side of the body first, and only later the left side. The one exception is with respect to tying one's shoe laces, where we take care of the left side first. The reason for this discrepancy is reminiscent of the tying of the tefillin on the arm, which is done on the left side of the body. (In the days of the Talmud, the shoe straps would be similar to the tefillin straps.) Why are the tefilin tied on the left arm instead of the right?
The kohanim in the beis hamikdosh did the Avodah (sacrificial service) with their right hands. Avodah done with the left hand would be deemed possul (unacceptable), and would have to be done over. Rambam (Hilchos Deos 3:3) explains the theme of the possuk "b'chol dracheicha da-eiy-hu". We ought not divide our activities into two areas, Kodesh and chol: mitzvah vs. secular activities. We should dedicate all of our activities towards the service of Hashem. Even our eating and drinking, our working for a living, or marriage and the raising of our children should all be done in the service of Hashem. All secular activities should be performed as a "hechsher mitzvah", as a means to enable us to lead a life of mitzvos. When we bathe, when get dressed, etc. we treat all mundane activities as if we were Kohanim performing the avodah in the Temple. We prefer the right side first, just as avodas hakorbanos (sacrificial service) had to be done with the right hand.
Avraham Avinu had the moral and ethical conviction, together with the courage, to put together a tiny little army to wage war against terror. Neither he nor his immediate family was personally endangered by the terrorists, but yet he intuitively knew that this was the correct route to take. Firstly, because one should not sit idly by while others are suffering from terror, and secondly because ultimately, this Hitler will control so much of the globe, that in the end he will terrorize him as well. Avraham's waging of the war was clearly an act of heroism, as well as his later refusal to accept any of the captured loot for himself. Both the waging of the war and the refusing of the wealth were fulfillments of "b'chol dracheicha da-eiy-hu". He really led all of his life in such a way as to reflect the tselem Elokim which he possessed. The Talmud (Chullin 89a) records a tradition that as a reward for Avraham's refusal to accept "neither a string nor a shoe strap", his descendants were rewarded with the two mitzvos of the string of the tzitzis and the straps of the tefillin. When we tie our shoe straps every day we reminisce over the heroism of Avraham Avinu. We tie the left shoe first to recall that because of Avarahm Avinu's Kiddush Hashsem in connection with the shoe-straps, his descendants were rewarded with the mitzvah of tefillin. We too should convert the secular sectors of our lives into hechsher mitzvah, in fulfillment of "b'chol dracheicha da-eiy-hu". There will no longer be kodesh and chol, rather the "chol" will become "kodesh".