I accidentally committed a serious crime for which I am facing a fairly severe punishment. But I would very much like to try to acquit myself in court or at least reduce the punishment for myself a little. Can you tell me how I can do that?

If you have evidence that you committed this crime accidentally, then by all means gather it and present it in a felony defense litigation. And if you cannot do this on your own, hire an attorney. An attorney will help you gather all the facts to defend your innocence and present them in a way that will get your sentence reduced https://arkadybukhlawfirm.com/practice-areas/criminal-defense-felony/.