working (workshy) chef here
I´d agree with: fresh baking powder (or better: cream of tartar+bicarbonate, dont open the oven door, sift flour from a height and fold in or use electric whisk and whip egg white seperately.

The only thing I could add is don´t use eggs straight from the fridge. Leave em out (if they aren´t already) for an hour or two.

It also depends a bit on the fat being used and your oven temp., it can vary a lot for domestic ovens depending on shelf/front/back etc.

If you need any foolproof baking recipes or anything else, let me know.

And good luck