There are a few things to keep in mind to prevent the dip from becoming watery: 1. For best results, make sure to serve the dip the same day you make it. See below for how to prepare the guacamole, salsa, and sour cream ahead of time, if needed. 2. Choose a brand of canned refried beans that is thick, yet creamy. This will provide a more solid base for the taco dip. I like Trader Joe's brand or La Preferida. 3. If using a store-bought salsa, pay attention to the label. Choose a salsa with descriptions like "thick" or "chunky," so it has less liquid to it. 4. If making homemade salsa, finely chop all of the ingredients with a knife, instead of blending it in a blender.