First, I want to say you really don't need any improvement. You already are a pro at makeup and your hair.
If you want a change, I would use charcoal brown eye liner and smudge it. Also, I would apply e/s around your crease and put a high lighter shade too. You have delicate features, so I would not put loud colors on you. The reason I say this is that people with delicate features can be easily over powered by strong e/s colors. But, if you had to use them, apply with precision and blend extremely well.
Your hair is a very pretty color. It's perfect. Runway models are actually getting away from highlights and all over color. Natural color is unique and more in style right now.
If you really just can't stand to not color it, please, don't allow someone put color all over it. It may make your eyes, features, and make up, fade out. Also, it's a major up keep. I have seen girls from High School that had beautiful hair color like yours color it once and I never saw their natural hair color again. Never. All I saw was blonde hair and not their beautiful eyes, skin or features. I was sad.
Hairstyle can actually bring out your hair color and your features more than anything. I would add a bangs and change up the length to give the hair more movement.
If you did want to go with a change in color. I would add only a few highlights. I do mean a few. Highlights can get where they look like a solid color too. Then, I get sad again. I think about my friends in High School. Their natural color hair was last seen when they were 16 and replaced with brassy shades of blonde. I am sad again.