As you seem to realise, you need to run smooth. Going through the first 400m in 62 not necessarily feeling comfortable, but not sprinting.
If you go out too hard the first 200m then you will slow too dramatically the second 200m. This means when you hit the bell you will be decelerating and it is difficult to then accelerate again to keep an honest pace to 600m.
You need to go through the bell smoothly and try to hold the next 200m; your deceleration needs to be drawn out across the race.
Work hard over the back straight, if you do not then hopes for a good time are lost.
As you reach the final 200m mentally surge again and then focus on maintaining your form, like your knee drive and arms, keeping the shoulders as relaxed as you can and give everything you have left over the last 100m.