As to the amount of salt, you don’t really need to be precise. Start with the lowest measure of salt and see how it works first before adding more to avoid irritating your lips excessively. After all, you just want to “plump”–not overdo it with painful, swollen lips.
My Homemade Lip Plumper
1 teaspoon of olive oil
a little bit of salt
½ teaspoon of vanilla
Just mix the ingredients together and rub on your lips. You will experience the effect soon after that.