Question. My first job in after effects is for a big trade show in London so bit OMG, is it best to start with 1080 x 1920 but what frame rate is it 29.97? I then need to save out as a WMV file HD
It's best to start with the technical specifications of what you need to DELIVER. Start with your end product.
You need to know how your AE work is going to be used. How it will be played back. How it will be displayed.
So you need to ask your client questions about frame rate, playback device, display device, delivery medium, media container and codec.
Once you know these, come back and talk to us. And if this really is your first gig, go hire someone to do the work and follow the link Mylenium provided. Why? Because if you're brand-new, and this project is due within the next six months, you'll miss the deadline if you go it alone.
After Effects is NOT the kind of application where you learn a couple of tricks and you're good to go. You need to know the basics. Without them, you're sunk.