Is "de Alfaro" under A or D?

The alphabetization of my last name is a cause of continuous confusion to everybody, myself included. The answer is:

In Italy, my home country, my last name used to be always alphabetized under 'D'. Moreover, I now have some papers with people whose last names fall between 'Alfaro' and 'de' in the alphabetical order, and I chose to be after them in the list of authors; hence, in the interest of consistency, I prefer to be always alphabetized under 'D'. My father, a physicist, also always alphabetizes our last name under 'D' in research papers.

Incidentally, almost invariably the papers in which I am a co-author are signed by co-authors in alphabetical order.

Should I write it with capital 'D' or lowercase 'd'?

Ah, now to the fine points. It depends. These are correct ways:

How do I get bibtex to come up with my name in the correct way?

Simple: just write
author = "de Alfaro, Luca"
This also works:
author = "L. de Alfaro"

Future Projects

In the US, everybody is free to dictate how their own last name should be pronounced. I am taking this one step further, dictating how it should be capitalized. Sooner or later, I will make up a declension for it (changing the spelling depending on the grammatical case), but for the moment, this is it. Enjoy!