Acrylic paint dries pretty fast, and I paint for hours- or over a few days. So it is essential that my palette stays wet for as long as possible. This is the set up that I use with my paint so it will last for up to 2 weeks. I recorded a video showing you how I do this setup, this is my first voice-over so bear with me!
This uses the Sta-Wet Palette (Around $17), which is marketed with a sponge and some Sta-Wet Palette Paper. I do NOT recommend using those, the sponge molds easily and the paper rips and dries out in some spots. So using it with heavy-duty paper towels (3 pack for $5) and a tempered glass palette (Around $30) works much better for me! If you don't want to spend the money on the glass palette, a tempered cutting board could work as well, you may need to find something for a backing though.
Also I like to call the piece of paper towel I put on top of the glass, the Moistmaker (if you've seen friends you will get this!)