Nice tips but I don't agree with this point.
Being specialized makes you stand out from the crowd and being "the person who does <foo> in the <bar> industry using his extensive knowledge in <baz>". Otherwise you are just "the person who does <computer-stuff> for all industries".
I agree that it's simpler to not be picky at the beginning but later on you should specialize - not just in technology but also in an industry.