Depends on if you're roll crimping or taper crimping.
If roll crimping, only enough to turn the mouth of the case into the groove. So you can't feel it when you slide your thumbnail down the side of the bullet and not feel the mouth of the case. If that doesn't hold your bullet in under recoil, the your expanding die may be over expanding your case.
Of course this only works on a bullet With a crimping groove or cannelure.
If taper crimping, you should adjust the crimp die to just "kiss" the mouth of the case. You should see a bit of shine on the case mouth. A quarter to half turn should be enough to hold a bullet in the case after it touches the case mouth.
Anything more is too much.