I was a librarian and archivist for hundreds of design of FPGA's (field programmable gate arrays) and 100 to 200 page schematic PCB designs. I have found that manual control of digital files is by far much easier then letting a program do it for me. All that is necessary is to treat your your digital storage as if it is a large file cabinet. You have a large file folder that you give a name to, inside that large file folder you have smaller fie folders. You name the smaller folders to either a an original designation of the digital files and other small folders for revisions of that designation.
To give you an example, I am a Ham Radio operator, I have radios from several manufacturers. I have all of the manuals in PDF format. I created a Main folder called PDF Files, inside that folder are lower level folders named for each manufacturer. Inside these folders are folders that list the name of the radio, below that are the manuals and firmware update files.
I know it seems to be a lot of folders, but it is easy to find anything I need. Also almost all programs have a way that you can define what directories you files go into. Microsoft Office saves all files to the director called Documents. I have gone into each program and set up subdirectories inside Documents so Excel does into a it's own subdirectory, Word in it's own, etc. If you look in settings for Picasa, I an sure you can define you own directory and subdirectories for your files, don't let the program control you, you must control the program to suite you.