The Sefas Emes quotes a question from the Ta"z that I have been unable to find, but here it is anyway: the Midrash writes that when Hashem sees us building our sukkah and preparing lulav and esrog he promptly forgets all our past sins. Only with the start of the actual first day of Sukkos, when our preparations have ended, do our sins start to count against us. This is why the Torah calls this day "yom harishon", the first day [of Sukkos], as it is the first day "l'cheshbon avonos", for counting transgressions. How can it be, asks the Taz, that during these intervening days between Yom Kippur and Sukkos, when we are engaged in mere preparations for mitzvos, we are protected from sin, while during the actual days of Yom Tov when we are engaged in the mitzvos themselves we are prey to aveiros?
The yesod that we see from here is that hachanos, preparations, are even more valuable than mitzvos themselves. A mitzvah is like lulav or sukkah has its week or day of performance, but the preparation for the mitzvah has no shiur limiting it in time or duration. It is an endless bounty of schar available for the taking.
Last night I went to do my hachanos and buy a lulav and esrog. Standing in front of me was a man maybe in his upper-20's, with a beard, peyos, nice black yalmukah and white shirt, and he was assisting his father, a slightly older clean shaven man wearing a little cap, a man who did not seem to be a baki in hilchos lulav, which is maybe why he had his son along. The conditions were crowded, it was late, and everybody seemed to be in a rush. So this young man quickly looked over every esrog out on display, grabbed the one he wanted, and then thrust it toward the seller and yelled, "Now make me a lulav to go with it" (or something along those lines), whereupon his father added in a loud voice, "Please". The son was "nishtomem k'sha'ah chadah" and then in a slightly abashed voice added, "Yes, please".
Baruch Hashem we live in times where a clean-shaven working man from the previous generation who knows he needs a lulav but perhaps never learned or never had an opportunity to learn the halachos of lulav can have a son who grows up to be a yeshivishe-looking Jew who is yodei'a sefer. But shouldn't that growth in yediyas haTorah also mean a growth and greater sensitivity in the realm of derech eretz [which is kadma laTorah!]?
So why do we do often witness the opposite?
It is relatively easy to find an esrog which meets the criteria of mehudar at least according to some shitos Rishonim. And when you walk around in shul with an esrog that everyone admires because of your eye for hiddur and the fact that your wallet can tolerate it, or when your guests admire the beauty of your sukkah, by all means feel proud of your mitzvah observance.
But there is a much harder hiddur to fulfill, and that is the hiddur of derech eretz. Did you buy a lulav without pushing the guy next to you in line (assuming there is a line and not a chaotic mob scence)? Did you build your sukkah without screaming at your kids who are tossing parts and decorations all over and are underfoot while you are dangling from a ladder? Did you decide to pull out your power tools at 11:30PM to work on your sukkah enhancements irrespective of your neighbor's desire to get some sleep (thank you to which ever one of my neighbors was doing construction around that time last night)?
If you are makpid on these hiddurim, your neighbors may not know, your buddy in shul may not know, your sukkah guests may not know. In fact, let's not pretend otherwise - by being Mr. Nice Guy you may get pushed to the back of the line and get a less than perfect esrog yourself! And then you come home and your wife says, "This is what took 2 hours in the seforim store for?". And in shul everyone thinks you cheaped out on a chinuch set or something, or maybe you grew that wilted thing in your own backyard.
But it seems to me that if these hiddurim are the ones you are makpid on, if this is how you are medakdeik in the hachanos for your mitzvos, then you can rest assured that your "yom harishon" will indeed begin with a clean slate, with all aveiros forgotten. Indeed, your lulav and esrog is a chinuch set -- an sterling example that will educate your children and grandchildren as to how a Jew should live with derech eretz and middos tovos, an esrog with a hiddur so beautiful that it cannot be purchased for any money in the world.