How long have you waited? You could have put too much on at once and is going to take awhile to dry. You can spray clear coat over it and let that dry and it will not be sticky to the touch, but the paint underneath won't have the air it needs to dry. I did that while painting my motorcycle. Put too much paint down and then sprayed the clear. One year later, I decided to repaint it and started sanding it down and the paint underneath was still tacky! Not good. Definately need light coats and dry times in between.

No, sand it off start again use thin coats, let dry well between then if you want put a couple coats of water based poly on it

NO!

The paint must dry first or if it does not dry, contact the paint manufacturers for advice.

I sanded all of the varnish off of an old desk and painted it with black acrylic paint. Because of the humidity (and probably because I added a second coat too soon) the paint is still sticky. I am wondering if I were to add a clear coat to my desk if it would make the stickiness go away. Maybe? Possibly??? THANKS