I just saw this, but that's good you do strides. Try to maintain being relaxed but also focus on your form. Accelerating for 30m, and then getting up to top speed, and then deaccelerating the last 20-30 meters.
I forgot to mention flexibility. I underestimated this a lot until just recently actually. My coach knows a sprinter who ran in the 2008 Olympics. I believe he ran a 45 or 46 400m. But anyways, he stressed the importance of being flexible due to your body being more efficient. In other words, more gains in strength and endurance. And obviously being less injury proned, because the last thing you want is to be injured and out for the rest of your season. Exercises like forward lunges with arm circles, touching your toes, gluteals, and hip abductors are good to do. Ask your coach even. Relax, but don't overstretch lol cause that's a thing. If you have any questions you can ask, I don't have much to say about your training out on the road, but anything for track with the 800 and 400 I could definitely help.