Flared base, no exceptions. A flare or a retrieval loop wider than the widest part of the toy, every single time. The rectum does not have a natural stopping point the way the vagina does. This is the one rule in this category that is not a preference, and it is why a bullet vibrator does not belong here.
Shop the width, not the length. Insertable diameter is the number that decides whether something is comfortable. A long slim plug is far easier than a short thick one, and the photos make everything look bigger than the measurements say.
Silicone only, and fully waterproof. Non-porous means it can be boiled and genuinely sterilized, which matters more here than anywhere else in the store. Fully waterproof means you can wash the whole thing under a tap rather than wiping around a seam.
More lube than you think, and thicker than you think. The body does not self-lubricate here at all. A thick water based gel that stays put beats a thin lube every time, and reapplying before you think you need to beats stopping because you waited.
A physical remote for the room, an app for real distance. A remote is instant and never drops a connection. An app is the only option for genuine long distance, but it depends on two phones and two connections both behaving. Pick based on which one you will actually use.
If vibration has not done much, change the motion. Rimming, thumping and rotating reach differently than a buzz does. This is the most common reason someone decides anal toys are not for them when the truth is they tried one kind of motor.
Go slower than feels necessary. Warm up with something smaller, breathe out on insertion, and stop entirely if there is pain rather than pressure. Nothing here rewards rushing, and starting small is what makes the bigger sizes possible later.