Hair colouring advice

[Mid Life Crisis]

Hi .i am looking for hair colouring advice from a male perspective !! have never had my hair coloured so any advice greatly appreciated . I have very short (no 1 clipper on sides and no 2 on top) dark hair which is starting to show a few greys .hence the reason i am considering having it coloured .the girls in my local salon thought i was daft when i asked them !!! which wasnt really the advice i was looking for !!

any help advice appreciated

thanks