Hi HSTech:
One of the main things to consider, regarding disk quotas, is whether or not you wish to block a client from saving anything else once they've reached their quota.
It's Murphy's Law that the one time anybody max's out their quota, that'll be the MOST important document ever created. And if they can't save it to their home directory, they usually panic and delete it (because they're usually too embarrassed to ask questions first)before thinking to call in help. And we all know who'll catch flak for that, don't we?!?! So my advice is to be very careful about checking off that box when you set the quotas.
One way around that is to activate the Warning check box on your quotas and give yourself a reasonable amount of available space when setting the limits. That way they'll be made aware that they're nearing the threshold and it'll give you some leeway and advanced notice in helping them plan their next move.
You'll also want to take into account that disk quotas calculate the disk space used based on UNCOMPRESSED file size. It may look to them like there's plenty of space available but if they're saving a large number of compressed files they could run out of space sooner than expected.
Do you have another disk availabe for ARCHIVE files? That way when they reach their threshold or ignore the warning and have now maxed out their quota, they'll have someplace to move their files to clear up some space for more recent docs.
So, you'll definitely want to educate the clients about getting rid of unnecessary files because it'll cause you some grieve if they're not aware. Sorry to be so long winded and I hope this helps a little.