Wow, ApfelKuchen! Thanks for the explanations.
My main idea to organize my library is:
2 Projects: iPhone Photos & Reflex Photos.
Then some folders by year. And inside a folder by date and activity like "06.04.2014-NewYork". This can be an Album. It doesn't matter.
Need you start with just two Projects at the top level, with everything else inside them? No. You have space for dozens of Projects, Folders, and Albums in the Library pane. Use it! If you have only "iPhone" and "Reflex" at the top level of the library, you have to drill-down to get to everything else.
Be careful of making a secondary (or even tertiary) criterion into a primary criterion. The subject of the photo is nearly always more important that which camera you used, or the date. Camera and Date are easily searched for - they're stored in the EXIF data that's part of every digital camera file (and the iPhoto/Aperture database record for that image).
What if you used both your iPhone and Reflex cameras in New York on 06.04.2014? Would you create a 06.04.2014-NewYork Album in both the iPhone Project and Reflex Project? Wouldn't you rather find them all in a single Album? What if you've photographed New York on dozens of occasions? Would it make sense to put all those dated Albums into a single folder dedicated to New York? Or maybe you don't care about date, and want to see all New York images intermixed. Maybe New York deserves to be at the top level of the Library. Maybe it belongs one level down, in the top-level Travel folder. This all depends on your priorities.
Pros may organize things differently - they may create a separate Library for each client. That keeps each client's work segregated from every other client (no accidentally mixing the Smith and Jones weddings). If they do many shoots for the same client, perhaps the Projects are labeled by job number. Or, they add the job number into the database record of all images as they're being Imported (very easily done), and create Albums dedicated to each of the client's products... and so on.
The key word here is
database - an organized collection of information. Where you
put the actual information doesn't matter nearly as much as how you
catalog the information, and how consistently. As long as the catalog knows where you've put the actual information and you can write a good search phrase/query, you're good.
There's nothing to stop you from creating several catalogs containing the same images (Albums, Projects); if it was an old-fashioned card catalog in the public library, the librarian would make several cards for each book, and put one in the Title catalog, one or more cards in the Subject catalog (say, "War," "Naval History," "Pacific Islands"), one or more in the Author catalog (multiple authors, illustrators, etc.)... The more cards there are, the easier it is to find the book.
Some of this can be done with Smart Albums. As long as you tag all the New York images as you import them, you'll automatically find them in the New York Smart Album regardless of where else you put them.
A common practice is to create "Selects" albums that contain images from many different Projects and Albums, and put those at the top level of the Library. I create Albums for photos that have been used in a particular publication, Albums created for slide shows, etc. Since the same image can be in multiple albums (without making physical copies of the image), why not?
And the last one... If i have a photo on an project and I manage color, curves, etc... and save it. Aperture will show the original and the modified in the same place?¿ and if I export the modified to the desktop for printing will it change the original on the aperture library? or will save both of them?
Thanks again!
To see the original and modified side-by-side, you would create a new Version of the image - one you edit, the other you leave alone. You can make many Versions of the same image (different crops, b&w, color balance, whatever). Aperture also has a feature called stacking, so that all versions of the same image can be "stacked" rather than spread out (until you need to spread them out).
Since the original is never modified, you can Revert to Original at any time - even if you're doing that to a Version of a Version of a Version.