I also came across a blog entry on "How to make Macarons" on "Serious Eats", which helped me out immensely. Here are a few of their key tips which I used when making my macarons:
-Sift your ingredients, multiple times if necessary. You want your ground nuts to be powdery. No lumps! Almond and icing sugar mixture may be pulsed in a food processor to make finer.
-Use old egg whites. No really, leave them out for three days at room temperature if you don't mind waiting for that long. Using fresh egg whites is more likely to result in macarons that are too fragile and flat. Read Veronica's Test Kitchen for more info.
-If the cookies form peaks on their tops after piping, flatten them with a wet fingertip.
-Let the macarons rest for a day before you eat them. They're supposed to taste better with a bit of rest. This might be the hardest rule to follow.
I decided to go with a basic, traditional macaron cookie with a Salted Buttercream Filling (remember my favored recipe from the Whoopie Pies?) Use Martha Stewart's recipe for the cookies (I did not go as far as to use "superfine sugar". My regular granulated sugar worked just fine.)
Pulse confectioner's sugar and almond flour in a food processor until combined. Sift twice.
Whisk whites with a mixer on medium speed until foamy. Add cream of tartar, and whisk until soft peaks form. Reduce speed to low, then add superfine sugar. Increase speed to high, and whisk until stiff peaks form, about 8 minutes. Sift flour mixture over whites, and fold until mixture is smooth and shiny.
Using a cookie scoop, scoop batter onto parchment-lined baking sheets. Let rest on counter at least 30 minutes. Bake.
While cookies cool, make Salted Buttercream Filling.
Place filling on flat half of one cookie and top with a second cookie. Place macarons in an airtight container with the lid cracked slightly. Eat the next day...if you can wait that long!