Smart collections instead of folders
Brendatn, I've just gone through the same process of figuring out how to manage my image files with a MacBook and an external hard drive. What what I've settled on is working well for me. It's based on John Beardsworth's smart-collections based
work flow, with a few tweaks, some of which are based on Clee's label system. The rest of this message may seem a little cryptic if you aren't familiar with John's system.
I import new images to a directory called "Lightroom_local" on my MacBook's hard drive and eventually move most of them (using Lightroom) to a directory called Lightroom_archive on my external hard drive. I don't use subdirectories in my two Lightroom directories, though I used to use them extensively. My reasons for abandoning subdirectories were twofold. 1.) They were inflexible and inconvenient. I used to have hundreds, maybe thousands, of separate directories in a date-structured organization. Keyword tagging images allows much more flexibility and power without any sacrifices beyond the time to enter keywords. 2.) They aren't necessary. I can easily find images by date (or other criteria) without subdirectories; that's the point of a database like Lightroom.
Two features of how I'm using Lightroom apply directly to splitting my files between my internal drive and a larger external drive, so you may find them useful. I have a smart folder called "Not local" in the "Overview" part of my workflow; it shows images in my "Current work" collection that are not on my internal hard drive, where they probably should be. If needed I can select all in that collection and drag them to my Lightroom_local directory (which could be trickier if I were using subdirectories).
The "Final Review" part of my workflow has two smart collections that I also find helpful.
"Remove from current work" shows images that meet the criteria: image in "Current work" collection and keywords aren't empty, and at least one of the following: labeled green (ready to use), purple (print), or have 1 or 2 stars.
A smart collection called "Move to archive" shows images in Lightroom_local that are NOT in current work and have 1-2 stars, and keywords aren't empty. This helps keep my local drive from filling up with images that I'm neither working on nor likely to want readily available.
In all, I've found that querying images based on metadata and other attributes, and saving those queries as smart collections when desired, is working a lot better for me than trying to organize image files into a finely divided directory structure on my hard drives. This forum has been invaluable in helping me figure out how to do that, by the way. There are other tricks I've worked out, which don't seem to fit neatly into this thread, for dealing with a substantial backlog of organizational work (key-wording and the like); ask if you're interested and I'll post in a new work-flow related thread.
Cheers,
Gregory