New painter - speedpaint is patchy

Hi! I just started painting my first „mini“ and realized that - even after a second layer of paint - the color looks rather patchy and uneven. In the photo, the shoulder plate is painted two times, the main body only once. I mix the Army Painter Speedpaints with water in about 1/3 ratio. What can I do better to achieve an even look?

Hi! I just started painting my first „mini“ and realized that - even after a second layer of paint - the color looks rather patchy and uneven. In the photo, the shoulder plate is painted two times, the main body only once. I mix the Army Painter Speedpaints with water in about 1/3 ratio. What can I do better to achieve an even look?