As we delve deeper into the world of paints and media and additives (mixing mediums), you will discover a whole spectrum of possibilities for your paint. You can go with straight paint our of the tube, liquid (usually acrylics) or you can add a mixing medium to enhance your paint.
If you want to use thick paint, add modeling paste or thick gel. Be careful when adding medium to your paints though, because there may be white tint in it so it could alter your color.
There is an interesting technique to add Marble Dust to your paint mix to create a paste that is a painter’s version of exterior stucco, for a rough stone-like texture. It’s so popular, you can get the Marble Dust Here