I would begin by googling up faux flowers, artificial plants, and finding out what the nylon/rayon/paper/silk like material used for those.
This page has a history of Faux Floral arts as well as a description of the manufacturing process. If you read how they are made you will get a lot of ideas for what you can and can't do based on how much time and money you plan to expend on yoru project. IE; you will most likely not be paying to have leaf shape dies custom machined for you out of tool steel (and you most likely don't have a die press to use them on either) BUT you could trace/draw your leaf shapes onto cardboard and cut them out for use as master patterns.--> http://www.answers.com/topic/artificial-flower
I am always cheap by necessity, not choice, so my thinking always seeks a lowest cost approach to the problem.
- make a wire armature for your branches and stems (make sure it can support the weight of the leaves)
- cut out leaf patterns from paper or cloth (paint them if necessary)
- glue up your leaves & fix them to the armature
- let dry and then 'pose' the plant to appear realistic
A craft supply stores often have faux flowers/silk flowers pre-made - you could always buy a sample and 'dissect' it to see how it was done.
PS: instead of rice paper - how about the tissue paper used for wrapping shirts/clothes in department stores - if you went 2 ply on the wrapping tissue and applied greatly thinned glue with a spray bottle between the plys you could probably get reasonalby strong results - or you could mix materials - cheesecloth 'mesh' bonded to tissue 'filler' over wire support might yield a nice translucent leaf.