It may sound typical, but really the best thing you can do is call a criminal lawyer.
Being arrested is a difficult and emotionally jarring time. You’re probably not going to be thinking straight, and you need someone who will not only be thinking strategically, but who knows the ins and outs of the legal system to make sure that ALL of your rights are protected.
A good criminal attorney will make sure that happens.
You also want to get yourself out of jail. Call a family member, or pay the bond to get yourself out. Then, once your out of jail, write down in as much detail as possible exactly what happened. Criminal cases can take up to 18 months depending on the seriousness of the case, and memories fade over time.
You also want to write down a list of potential evidence and witnesses. Police officers often don’t conduct a thorough investigation. That’s why you want to give your lawyer as much information as possible to do an independent investigation. He/she will want to speak with defense witnesses, take pictures of the crime scene, request 911 calls, and prepare your defense.