So, for the very first dyeing of my life I want to do something kinda fun, so I want to put a blue ombré in my hair. I'm going to get it lightened and dyed at a salon, bc I am 100% positive it would look jacked if I tried it myself. I've taken a liking to the way blue velvet looks, but I'm open to other suggestions. No neons though, they're not really my style. In your experience, how long did blue hair last, how was the fading and how do I keep it looking fresh for as long as possible? Thanks for all and any advice!

Additional details: I have straight virgin dark brown hair down to my butt. I use coconut oil on it once every week of more, and I keep washing to the minimum so it is extremely healthy. It's fine-medium thickness, but I have a lot of hair. It also grows like a weed, and has minimal split ends. I could probably dig up a picture if necessary.