If you've forgotten to leave out the butter to soften to room temperature, pop it in the microwave for eight (8) seconds. Purists may shriek at that, but I've done it and trust me, it doesn't impact the recipe.
It goes without saying, but do scrape down the sides of the mixer bowl at each step -- it makes a huge difference is getting the ingredients well-combined without over mixing (which will over-activate the flour glutens and lead to hard, dense cookies.
I recommend rolling the dough 1/4 - 1/6 inches thick to cut cookies -- anything thinner than that is likely to be too brittle for decorating.
Cooling helps the cutouts retain their shape when baked -- I don't recommend skipping this step unless you're really short on time.
Dough can be stored in the refrigerator up to 2-3 days, but I've found that baking the same day as the dough is mixed always results in the best cookies.
FAVORITE SUGAR COOKIES
2 cups unsalted butter, softened
2 cups sugar
2 large eggs
3 teaspoons vanilla extract
5 cups all-purpose flour, sifted
1 teaspoon salt
In the bowl of an electric stand mixer, beat together butter and sugar on medium speed for 1 minute until light and fluffy.
Add eggs and mix (stir -- lowest mixer setting) until combined.
Add vanilla extract and mix (stir) until combined.
In large mixing bowl, sift the flour. Add salt.
Add in the dry ingredient mixture (stirring for 30 seconds to minimize flour explosion all over you and your countertop) and beat on medium-low speed until fully combined.
Roll dough between two pieces of parchment paper. Place on baking sheet and refrigerate for one hour (minimum).
Preheat oven to 350F.
Roll out the dough further if you need to, and cut out cookie shapes. Re-roll scraps and repeat.
Place cutouts on parchment paper-lined baking sheet at least 1 inch apart and put back into the fridge for 10 minutes.
Bake 8-12 minutes depending on cookie size (edges should be golden brown)
Remove from the oven and let cool for 2-3 minutes before transferring to wire rack to cool completely.
Eat as-is or decorate with royal icing, fondant, sanding sugar, etc. Store in tightly sealed containers (in-between layers of parchment paper) or wrap individually in treat bags (tied with ribbon is especially nice).