1 Sip water or sugarless drinks often. 2  Avoid drinks with caffeine, such as coffee, tea, and some sodas. 3  Caffeine can dry out the mouth. 4  Sip water or sugarless drinks during meals.
persuasive - intended or having the power to induce action or belief; persuasive eloquence; a most persuasive speaker; a persuasive argument. convincing - causing one to believe the truth of something; a convincing story; a convincing manner.
I believe the word you're looking for is  persuasive . This is an adjective. Someone who is able to speak (not speech,  speech  is the noun) very well and uses words effectively to influence people could be said to be persuasive.