Cock rings are usually made of silicone so they can be stretched over the penis and testicles to (a) help maintain an erection, (b) make said erection harder by limiting blood flow, and (c) if it has a vibrator feature, stimulate your clit during penetrative sex
Not great for: Just clit masturbation. They’re fine and you might like it enough for just clit masturbation, but generally speaking, you don’t want to be tied to a toy for all your clit masturbatory needs.
Tips/how to use: Try using one on your clit during missionary or doggy while your partner enters you vaginally. You can also hold it in place during girl-on-top as it’s less likely to fall out of your hand while it’s attached to you.
Flatter-shaped panty vibrators are usually clitoral (like 95 percent of them are such, but you’ll find a few that also have small internal components that can be worn inside you), that sandwich between your underwear and your vulva for clitoral stimulation.
Not great for: Coupled penetrative sex. They’re way too bulky for you to feel the vibrations from the toy while being penetrated. While you can always slide your undies to the side to still “wear” underwear while having sex, the bulkiness of these toys mean you can’t really slide to the side to allow entry for your partner while still feeling the vibrations.
Tips/how to use: Give your partner the remote (or if you have a model that lets someone control it from anywhere in the world, get them to download the app) and give them the controls while you’re subject to their whims.
Not great for: Blow jobs or hand jobs (you won’t reap the benefits of vibration on your hand or mouth) or use as a standalone clitoral vibrator (there are way more efficient options for that)