You should be too. In particular, don't emulate the style of well-known preachers 40 years your elder. For one thing, it just sounds odd when a young preacher talks like an old preacher. For another, those old preachers often borrowed their style from another older brother that they admired, so the style may be twice that old by now. Don't let your delivery distract from your message.
Truth is timeless.
The sad fact is that just being a preacher, and doing it fairly frequently, does not automatically make you a good speaker. Be yourself, and talk in a way that is effective for you and your listeners. You can be enjoyable to listen to, but not effective in carrying the argument. But if you are a good speaker, you will be effective, and as a happy side benefit, your listeners will also enjoy listening to you. Of course, you can have some effect by sheer strength of your message or your personality.