Decorating and Design - Murals - how to paint them

Hi, I would like to paint a mural on my living room/ hall wall. Is there anyone on this site who has done this & can give me some pointers? It will be a family trees with interlocking branches (I hope). How do I go about this. If it does not work out, I'll just paint over it.. but have been wanting to try it. I would also like to antique over it, to make it look really old, so any suggestions on how to achieve this will also be appreciated.

I'm going to move this to the design forum, maybe someone here can help.

Thanks. I was going to post there, but since I have my design, was wanting information on paint, prep, etc... decided on this forum. I have drawn (copied actually) the trees I want... and have them gridded, ready to transfer to the wall. Just wondering how to make them look old when finished. I was thinking of using a colored stain, then a water base satin poly as a finish coat (stuff I already have in garage).