The best rule of thumb is that beginners should start with a toy that's smaller in size. Small plugs should be roughly the size of a finger or two for easy insertion, so you can gently stretch the tissue around your anus. Eventually, you may want to work up to larger plugs, which can get as big as a fist. Dr. Fleming suggests choosing a small metal or glass butt plug, specifically, because they’re nonporous (so pathogens, like certain bacteria, have a more challenging time settling into the plug) and easy to clean. Both materials are also safe to use with any type of lube, whether water-, oil- or silicone-based. What are some tips for trying anal play for the first time? Finally, Dr. Fleming stresses that anal play isn’t something you get right into. “I can’t recommend enough the importance of only introducing any anal play when you’re already highly aroused,” she says. When you’re aroused, your body relaxes—including your anal sphincter. So the more turned on you are, the more enjoyable anal sex will be.