Ladies please, help me quit smoking?

Just fire off any tips you have. I've only been smoking a couple of years, literally, and I only smoke 1/2 pack a day (that's the absolute max). A lot of people insist I should have no problem but if you've ever been a smoker you know it's not easy to quit. I have to quit by July 24th- it's all my little sister wants for her birthday and I want to do it to better my health for my future pregnancy. 
Okay so, I know there are some mommies or mommies to be that had to quit nicotine. No advice is dumb- I'll take any I can get. I cannot have another cigarette after that date. Help me, girls... Tell me you've been here before...