Well, I’ve had the same problem with my Macbook. Until I figured out a fix, I had to struggle to get the cursor moving easily on the slick surface, and any moisture on my finger would make the pad sticky, even though the trackpad was smooth.
So I have a fix, but it is very un-Apple like. Well, maybe it is Apple-like, because it is simple and quick. Maybe this is what they do in the back-rooms of the Apple Stores and Apple repair places, who knows?
The secret weapon? Sandpaper. I use a small piece of 150 grit sandpaper to very gently rough up the plastic surface of the trackpad. You do this VERY carefully. And don’t get any sanding residue in the keyboard. All it takes is a few swipes to take the smooth surface off the plastic.
You don’t, of course, want to sand through the plastic of the trackpad. Just a few circular motions with the sandpaper will rough up the plastic to where it has a little friction and gives more resistance. And that will give much better cursor control.
So find a scrap of sandpaper somewhere and give it a try. It should be 150 grit or finer, but anything like 400 grit won’t do much. Or, get a Scotch-Brite, the kind you use in the kitchen for scrubbing; they are made of hard plastic and are safer then sandpaper. They won’t be as abrasive, so they are safer to use and may scuff up the trackpad just enough to make it easier to use.
I’ve had to do this every year, it seems, for my old Macbook. Just remember to sand or scuff it a bare minimum to give the trackpad some friction. All you need is a little bit of friction to make the plastic not slippery anymore.