I really wanna be a warlock in wow but i give up because theyre mana drains so fast!?

could some1 explain to me when theyre supposed to be fun and the different advantages, specs, abilities ect.. id really appreciate it. i just cant stand how im an undead warlocks and i can only kill like 2 people starting out and have to wait for my mana to come back D= ive noticed druids have the same damage but use up like 12 % of wat locks use so some1 please tell me wat advantages id have picking a warlock and whether it will be fun throughtout or make me wanna start over by the time i reach lvl 20