You can't really "handle" a flight attendant, grumpy or not - your interactions with them should be straightforward and strictly professional. If one gives you bad service, deal with it afterwards with customer service. For example on United, if the FA blows off the preflight drink in first, don't argue, just get your 15-25k miles later. The only exception would be if the FA refuses to enforce your seat assignment when a poacher tries to encroach- then it is perfectly acceptable to talk to the purser or GA. Remember, the FA can RUIN your day, keep it civil and professional.