I was admonished for putting my duty free rum in the overhead bin, which fell out onto my head when the FA opened the bin. 'This is why tell you to put these items under the seat'. [er you didn't tell ME, but never mind]

As noted, the FAs can tell you what they like....

Obv. thing to do is wait till after take-off and the seatbelt lights are off to stow your second bag - that way you can ensure everybody else has had their chance to get ONE bag stowed.