I decided to give another try when it comes to gradients, and I learned something:
some polishes are too sheer and water-y for this. I used Sinful Colors Snow Me White as a base and Kiko 296 and E.L.F. Mint Cream as gradient colors. Well, Mint Cream's formula made everything turn out worse.
Not to mention that photos can make even the most decent nail art look awful. I'm still posting this because maybe someone can learn from my errors (and to prove you that I'm still alive and nail paintin' ).
I added Kiko 644 on top (from the Sugar Mat line) for a textured effect.