Running a 400m

Im trying to figure out exaclty how you are supposed to run a 400m. Some people are saying that you sprint your first 30 then relax and then some say sprint the first 95 and so on. I right now just sprint until I feel comfortably ahead then relax the backstretch then when I get to 150 I start to really go hard again. That’s how I ran my 48.67 but I want to go faster and I want to see if there are other ways. Any comments?