Speak more clearly opening your mouth more. Men tend to mumble.
Don't use contractions
Men tend to start with a bang - "OK everyone - listen up" women tend to approach it more gradually "Can I have everyone's attention please"
Men issue orders, women use requests (see previous example)
Pay particular attention to the sounds for S and T. They are very different from males to females
Do not be "cool". "Yo man!" should be replaced by "Excuse me". Generally avoid colourful four-letter anglo-saxon words like sh*t, f**k, etc, etc. Whilst some woment do use them, most do not and they are considered very coarse when women use them.
As Axelle says, express emotion. "How are you today?" - male answer "OK", female answer "I feel good today"
Even if that is all true, (and it's not, my female bosses issue orders just like my male bosses do, the American Southern dialect is full of contractions used by both male and females, starting with Y'all) it has nothing to do with dialect unless you are using that word for something far different than it's common linguistic use - which is about pronunciation patterns and speeds. So someone from New York will use far more words per minute in casual conversation than someone from Alabama, Mexican Spanish is much - mucho - faster than Continental Spanish. There are regional word choices - is that a 'pop', 'soda', coke (used as a generic for all soft drinks in some areas), do you put your groceries in a 'bag', 'sack' or a 'poke' - but I'm not even sure that is true dialect, it's much more about how the words would be pronounced rather than the choice of word itself.