Add the sour cream first to a bowl, then add 1 egg and whisk together.
Once the sour cream and 1 egg have been whisked together, you can add the rest of your eggs. This keeps the sour cream from clumping up. It's pretty ugly looking if you add the sour cream into the eggs and they won't be as fluffy.
Add butter to a skillet and melt on low heat. Keeping the heat on low, slowly add the egg mixture to the MIDDLE of the skillet. This creates a barrier of butter around the eggs, which helps prevent any eggs sticking to the pan.
Don't bother the eggs. I know it's hard and you want to take that spatula and move them around, but give them some time to cook on the bottom first. Just a few minutes, then using a spatula start on the outer edges and push the spatula towards the center. This pulls the cooked eggs to the center, and allows any runny yolk to cook. Gently start folding the eggs, bit by bit. You do not want to bother the eggs too much. Just let them do their thing.
Pretty soon you'll noticed the eggs are cooked and ready to plate. Don't over cook the eggs!