I use metal dies such as those from Spellbinders and Marianne Design quite a lot. Some of them drive me to distraction when trying to get the card out of the die and I often end up tearing the more intricate ones. I've tried various ideas submitted by other folk over the years and even some of my own such as spraying the die with silicone lubricant! Furniture polish was one of the best but here's something else I've come up with.
Years ago I bought some non-stick material for lining my baking tins. In fact it's pretty much the same stuff that's used now for the non-stick brown craft mats. Anyway, I had some odd scraps so I tried die-cutting with it and left it in the die. The next time I cut some card it almost jumped out of the die on its own! After putting it through a few times the liner was nicely set into the die and I find that even the subsequent embossing is fine. I use fairly lightweight card for die-cutting so not sure how well it would work with thicker card.
Having used up all my tin-lining scraps I wasn't about to cut up my non-stick craft mat, so I headed off to one of those famous Pound shops. They sell the non-stick sheets. They are much thinner and therefore perhaps even better for my purpose than my original thicker liner.
Here is a photo of my Heartfelt Creations lace die (made by Spellbinders) with the pound liner inside and a sample of what I've cut using this method.
I have to say, to cover myself, that it is NOT recommended by the die or die-cutting machine
manufacturers and, like me, you would use it at your own risk.