Read the recipe all the way through first. Preheat the oven, and assemble all ingredients and equipment before creaming, folding, baking and such. These basic strategies make the actual assembling of a cupcake much faster and easier.
If you’ve had suspicious results from past recipes (burned or still-liquid by the projected finish time), it’s worth buying an oven thermometer. Some ovens can be off by 75 degrees F (any more than that and you will likely need repairs). Even a perfectly calibrated oven can have “hot spots,” so plan accordingly: Place single tins on the middle rack and rotate halfway through baking. When baking two tins, place one on a rack in the upper third of the oven and the other in the lower third, and switch and rotate tins halfway through. And except for this rotation, keep the oven door closed at all times to avoid heat fluctuations.
Baking powder and soda have expiration dates on them, after which they lose their lift. It’s best to replace them after six months of usage. All spices lose their potency after a while. Old flour is also suspect — replace your bag if it’s been around longer than eight months.
Experienced cooks are sometimes the guiltiest of trying to fiddle with recipes, but this can cause problems in baking, where recipes are a bit like scientific formulas. Cutting the sugar for less sweetness is tricky because that sugar is also responsible for producing a certain texture and moisture in the cupcake. Swapping dairy or cocoa can be problematic too — baking powder or soda may not get activated. Swapping oils, sweeteners, like molasses or honey, or types of flour can each cause different results. Cautious substitution can lead to tasty discoveries — and the occasional inedible hockey puck — so experiment when you don’t mind unexpected results.