I'm try to improve my blocks start but for some reason I'm finding it hard. I'm quite tall but I good with jumping and improving my weights. Is there any drills I can try to improve this?
Also try strengthening your quadriceps, since they are the main driving force in block starts. There's an exercise for improving your starting strides: Stand with your toes touching the line, then slowly lean forward like you're going to fall on your nose (something like MJ in Smooth Criminal :) ) Lean until it's time to start running.
YouTube is also a great resource for these exercises.
First of all, only your reflex matters in improving block starts. I suggest doing as many starts as you can, and having someone time you with a stopwatch. Try to be faster in leaving the blocks. Being low initially helps in gaining speed, efficiently and swiftly leaving the blocks.