tile over concrete porch/patio area

We plan on installing tile on exterior, but covered porch/patio area. In the past, the concrete has been painted with exterior concrete paint, which is extemely slipperly when wet.
*How should we prep the surface to be sure the mortar adheres?
*Is there any special mortar we should be using as we do occasionally experience freezing temperatures here in No Central Texas (No of Dallas).
Thanks....