I'm trying to install a new kitchen faucet which has unthreaded copper input tubes. How tight should the compression nut fittings be? They're brass fittings with a brass ferrule.

I tried tightening them hand-tight plus a quarter turn with a wrench, and the supply lines slipped off the tubes under their own weight. I tightened them a little more and they stayed, but they rotated freely around the tube. A little more and they rotate around the tube with some friction when I try to turn them. I tried turning on the water and they dripped a lot.

Should the fitting not rotate around the tube when it's tight enough? If I just keep tightening a little at a time until there are no leaks, will that be tight enough so they won't leak in the future?

At the shutoff valve end of the flexible braided PVC supply lines, the 3/8" compression connector has a rubber cone inside. The instructions for the lines said to tighten them hand tight plus a quarter turn.

But since I had to flex the line to get it to line up at both ends, I had trouble tightening the nut by hand while keeping the first bit of the line straight. I tried to figure out where "hand tight" was by tightening slowly with a wrench, and seeing if I could still loosen the nut by hand after each quarter turn. So I might have gotten it wrong.

There's a small spray from one of them when I turned on the water. Is it too tight or not tight enough? What are the symptoms of overtightening? Do I have to throw out the line if I overtightened it, or can I just loosen it?