This rule is one that can make a big difference to how your make up turns out.
Cream on cream.
Powder on powder.
To break it down - this means if you use a cream or liquid foundation, you must continue your make up with creamy products.. cream blush, cream eyeshadow (which by the way, only lasts 5 minutes) etc...
Same goes for powder.
There is only one way to work around this..
If you use a liquid foundation & you then want to apply a powder blush/eyeshadow, you must first dust on some light translucent powder over the area before appling the blush/eyeshadow. You can't go straight onto the creamy skin with a powdered colour, well i mean you CAN, no one is forcing you, but i definitely wouldn't advise it, otherwise it will crease up & start separating.. kind of like oil & water!
& that's NOT a good look!