Becoming a police officer?

I want to be a police officer in the near future. I am currently in the military and get out in about a year. I am Infantry and have a deployment to Iraq. I worked at President Barack Obama's Innaguration as security. I have done drugs before (well just smoked weed) and don't have the greatest credit. I hae never been convicted of any crimes or arrested at that. I have 2 speeding tickets and that's all. I would like to get on to Baltimore city, DC, Columbus OH city police or Ohio State troopers. Should I have any problems?