You won’t violate any rules. I presume you’re not going to a traditional Protestant Church, e.g., Lutheran, Presbyterian, etc. and instead are going to a non-denominational community. Don’t expect any communion service, but don’t participate if they have one, they’ll have one every month or so, usually the 3rd Sunday of the month.
Mostly, expect some guy in rolled up sleeves or casual clothes to welcome you from a stage, announce some “amazing things we’re doing this week” (feeding the homeless, having baptisms, giving out tracts, etc.) then reading a “call to worship” i.e., a Bible verse.
This will intro the band, which has been quietly assembling behind him. Said band will play, the words of the song will be up on a screen. Depending on the computer sophistication of the church, the screen may have things on it (helicopter view of the Rockies, volcanos, the sea, etc) while “Our God is an Awesome God” is rocked out. Expect raised hands and rocking motions from the community assembled.
After 3 or 4 songs the “teaching” Pastor will appear, he will read a sentence from the Bible (generally New Testament) then exposit it, another sentence, another exposition, etc. When it’s over you will have heard a great motivational talk.
At the end of his talk, Pastor will pray (the prayer will be a restatement of the sermon in the form of a prayer). As he prays the band will silently reenter the stage. There will be one more song then Pastor will come out again and do a mini-prayer of the sermon and post sermon prayer and dismiss the assembly. And then everybody will tell you how awesome it was.
Then at 5:00 p.m. you can recieve the Lord of the Universe, your creator, into your mouth, body, blood, soul and divinity and the sermon won’t sound so good.