organizing iPhotos professionally?!

gents. i am about five years overdue on organizing my iPhotos. i am coming from APERTURE which i used rather idiosyncratically. or maybe i just used it like i still had a PC.

anyway i MOVED photos from the Aperture boxes (or whatever they were called) when they got imported and then i placed them in a THEMATICALLY NAMED folder.

so each image was in a folder.

then i created ALBUMS and sometimes published an album to FLICKR or i exported images to my desktop where i used them to create things.

i realize this is non-standard and i was hoping for some "live human" response to how i should think about using iPHOTOS.

for instance today i went to export some images to the DESKTOP in order to paste up a PAGES document and i realized i really need a way to MARK or LABEL these photos once i find them so i don't have to go looking for all of them again.

can i LABEL images in iPhotos with a term? should i create an album? are there more tools than simply putting a heart symbol on something like i do on the phone?

THANK YOU