Heavyweight, matte photo paper works best! Glossy photo paper and smooth card stock work as well. You can find quality paper at office supply stores (like Office Depot or Staples) and superstores (like Walmart or Target).
To get the best results, please make sure to disable color correction, “color management,” or “autocorrect” in your print settings. On HP printers, set color management to “Application Managed Color.” If you use a professional printing service, make sure they disable color correction.