I've been trying to re-learn cursive for about the past 6-7 years and am still not thrilled with it. I find that I tend to try to write too fast, and this makes it sloppy. Something about the connection between brain and paper has been accelerated by typing. When I am able to slow down my writing, so that more thought goes into each word, it looks good. But practice, practice, practice!
Also, try different pens and different paper. I write better with "rolling ball" pens, the kind where ink just sort of flows out of them, rather than cheap ballpoints where you have to press down on the paper. But cheap paper causes the ink to bleed and look messy.