You want to save your work in the absolute highest jpeg quality always. Lower jpg quality results in a compression scheme that will create pixelation and color changes where you don't want them on your art. You may not see this on a monitor but it will print.
 
The best way to save your file size is to cut down the "physical" size of the piece. If you are creating art for a greeting card only, you can create it in the actual size of 5x7 inches or 7x5 at 300 dots per inch (or a total pixel size of 1500 x 2100). This is really the minimum size you should allow for the absolute best print quality.
 
3 MB is not very large for a print file.  
 
If you are saving another image out to be used on the internet only, change your dpi down to between 72 and 92 (I still use 72 even though it's old school). Then you can use the compression settings. I would not go below 80% (or 10 - I think that's close but i'm not looking at the program right now). and you won't notice any visible difference. But certainly don't send it to print at this size.
 
Cheers,
Mishka

There has been a few occassions where I have made a card and it has been bigger than 3.85mb which means I have to go back and tweak. Sometimes I wish we could upload more than 3.85mb but I guess a lot needs to be set.
 
Cheryl

Thanks for the info, Norma...this might come in handy for me.  Very good Artist Tip.  
Linda