Warm — not merely room temperature — eggs and dairy are critical to the success of many baking projects, but particularly cakes. Warm (85-degree) eggs let yolk emulsifiers flow, keeping batters smooth and uniform. Soft butter evenly coats flour granules, and warm milk, well…that doesn’t do much other than help keep everything else warm (but it’s still important).
Getting your eggs nice and warm — quickly — is an easy thing. Just put the cold eggs in a medium-sized bowl, get some good hot water flowing out of the tap (don’t worry, you won’t cook them) and fill up the bowl. 7-10 minutes later your eggs will be just about perfect.
Milk? Again, easy. A cup of refrigerator-cold milk will get blood warm after about 25 seconds on high in the microwave.
Butter is a little trickier since it melts so easily, but two or three bursts of ten seconds is enough to soften a stick and a half to the point of usability.
Make the warming of your ingredients a reflex before you set to work and you’ll have made an across-the-board improvement in your baking.