OP, I'll make it simple for you.
Pick the state you're in, and Google "{state name} 529 plan". You want to invest directly with them, and not via an intermediary. You want to put it in your state for the tax benefit (you can always move it later to another state).
Then, put it in the investment plan NOT the prepaid college plan. More flexibility, even for private high school (because of the tax bill passed last December).
Then, for the investment option to choose within it, pick the one based on the year your child will enter college, like "Portfolio 2033" or something like that. The investment managers will adjust the risk level as the date approaches when you need to use the funds. Your investment may go down some years, but over time it should go up.
Done. Now enjoy your weekend and no more need to worry.