I agree with not using jpg. First thing I do is save to png. Non-lossy
format has the advantage of being widely used on the internet in web
pages. I have been told that files are larger than when saved in jpg
and that I blame on compression that makes lousy picture quality. Try
png and see what you think. png also works for combining different
forgrounds and backgrounds because it offers transparency.

I sometimes wonder if gimp would be more popular if people would bother
looking over and following some of the tutorials on the gimp website.