Planning for a 2nd Baby

I am a mother of one . She is only 1 year old . I miss pregnancy , the entire process . I am a smoker apparently when i found out i was pregnant with my first child , i stopped smoking after 2 months . I am thinking of another child lately and i have started smoking 7 months back , i am afraid my smoking will cause my baby to not be born healthy . As a mother , i want my child to be healthy and thats important . What shall I do ? I do know the first thing is to stop smoking . What else can i do ? More over i am 20 years old this year , planning to go back to school next year .