I've failed a couple times at ranch dressing until I found this recipe for Creamy Lemon Ranch Dressing on the back of a bag of Dole iceberg salad. I modified it a bit for regular ranch. It reminds me of the ranch dipping sauce at Arella's Pizzeria.
Creamy Ranch Dressing
1/2 C mayo*
1/4 C sour cream*
1-2 T milk (use 1 T for lemon ranch (below) and up to 2 T for regular ranch)
1 1/2 t white wine vinegar
1/2 t dried minced onion (I think I just used onion powder)
1/2 t garlic powder
Pinch of dried dill weed
Salt to taste (I used 1/2 t seasoned salt)
1/2 t pepper (omit if doing Lemon Ranch (below). I actually didn't have any pepper, so I left it out.)
*If you use light products, you may need to adjust (lessen) your milk.
Creamy Lemon Ranch Dressing
To the above add:
1/2 t lemon pepper
1 T fresh lemon juice