This is entirely dependent on the circumstances surrounding the offense. For cases involving possession of prescription medication without a prescription, this can be as simple as providing documentation or evidence that you were in fact authorized to possess said medication. For other cases, it is possible that presenting a clear case to a judge as to the reasons why you were in possession, especially emphasizing the circumstances leading up to the arrest, can sway a judge to potentially dismiss charges or explore alternative punishment.
Additionally, showing evidence that you are working to change the habits and decision making that originally led to these charges in order to avoid them in the future will help present your case in the best light possible, increasing the chances that you will have charges dismissed.