A cool trick I learned from I think it was tedster.
When reducing images hit the sharpen button before resampling and resizing and do it in steps rather than all at once. In other words to go from 600x600 you would hit sharpen and then resample to 400x400 then hit sharpen and go to 300x300 and hit .....until you get where you need to be.
Its an experimentation kind of thing as too much sharpen will pig out the file size and do you no good. Thats when 400000 levels of undo come in handy and one reason you gotta have as much ram as you can and even set a scratch disk to another drive. Ram is really cheap right now too. 256meg chips for less than a hundred bucks.
As oilman said...save, save, save.
Also a good practice is to copy your font folder to a backup source. And your MM extensions folders in DW and FW too. I have learned this the hard way. Write your work to a cd if you have one.
I partition my drive into about 4 parts. I keep windohs and all the application on c drive and make an image with Norton Ghost. I then keep all my working directories on drive f or d or whatever. That way, not IF BUT WHEN I have to restore c drive all I have to do is drop in the last image I made with Ghost and I'm right back in bidness ;) in 20 minutes. I never lose the data only the applications...follow me? This is not infallible as I recently learned because you may run into trouble with the mbr as well ;). Back up the data you have on f or d drive regularly as well.
BTW you can also use a drive to store all those templates you use that are on 4 CD's right now...like AutoF/X PhotoGraphic Edges. Which if you don't use you might want to look into because it makes ordinary pix look really good.