Butter: Like always, I'm using unsalted butter because I find the unsalted butter has better flavor and gives my baked goods a better texture. But feel free to use salted butter but cut out the additional salt in the recipe if you decided to use salted butter.
Cold butter: cold butter will guaranty the flaky texture in your scones. What I like to do is to cut my butter in 1/4 inch cubes and pop them in the freezer for about 10 minutes before making the scones. You can also chill your scones for about 10 minutes while you're preheating your oven.
Blueberries: I prefer fresh blueberries, but if they're not in season or you leave in a state that is hard to find fresh ones you can use frozen. You can also use fresh cranberries for the holiday season or use dry fruits and nuts in your scones.
Heavy cream: heavy cream will give your scones rich and soft texture. Scones are known for dense cake texture, but when made with heavy cream, you get less doughy and softer texture due to the high-fat content in heavy cream.