Best diets to see progress with working out ?

I don’t know too much when it comes to fitness and exercise but I’m ready to start! I am NOT looking to loose weight. I am looking to tone my body by getting a flatter tummy & bulking up my legs and butt. I already have naturally bigger thighs but they’re more jiggly then I’d like them to be! I hear about all sorts of diets like the keto diet, diets with high protein or lots of fruits and veggie, gluten free etc etc but I’m not good when it comes to buying certain food or knowing what to buy. What do you like? What worked for you? & how long before you saw progress with working out ?