There are already plenty of resources on this topic available. Here's the basics, in my opinion:

Many people overemphasize the importance of things like how to sit or walk, while neglecting far more important gender cues. Extending your pinky when drinking, or pointing your toes when you cross your legs aren't going to get you very far. You'll probably look more like you're mocking women doing stuff like that.

Watch other women who are your age, size, and socioeconomic peers. Take cues from them.

Smile and laugh a lot.

Have good posture, but don't be all rigid like some uptight librarian.

Keep your knees together and elbows in.

Hold your head up-- don't crouch down or hunch your back.

Broad shoulders look worse when hunched forward than pulled back.

Listen carefully to what people are saying. Look people in the eyes when listening and talking.

People pick up on your insecurity. Just try to be friendly and confident, and you'll do fine.

Primary net resources

I do not answer questions about comportment. For those wanting more practical information, please go to these pages:

Tamsin has written a nice piece called Thoughts on Feminine Movement.

Denaë Doyle has a great commerical site on Feminine Image, including a professional coaching program. Denaë has just released a new 50 min VHS or DVD: Feminine Movement by Denae Doyle.

As part of their part-time role-play, many crossdressers enjoy exaggerated feminine mannerisms. If that's what you are interested in, here's a list of links to makeover and role-playing services set up like old-fashioned courses on etiquette, poise, and protocol, etc.

Check this out for a more scientific look at range of biomechanical movement in different body types.