Accounts Being Hacked!!!!

Just a quick heads up here. I just had an email sent to me saying someone is trying to access my Steam a/c from another pc.
It requested me to logon and change pw immediately. This I have done. It recommends changing pw very often as this is becoming an increasing threat ALL the time.
Well I don't know how often is very often??

Any ideas how often a pw like steam should be changed???

I'm thinking at least once a month now after having my Uplay a/c stolen!!!