Hi - making brownish vines can be a really nice look, and makes leaves show up well. The nice rich medium brown (I don't know the number), transparent ambers, blacks and brick red all look great.
For green vines, one of my favorite greens is petroleum. It is *slightly* stiffer than some other greens. It doesn't go muddy with reds and yellows but does react strongly with ivory. Mosaic green, on the other hand, seems to react to everything and is REALLY, REALLY soft, but it's such a gorgeous deep colour... try this only if you are able to encase it (try dark emerald green). It's really annoying to encase mosaic green because if you leave the tiniest hole it'll ooze out and smear over your surface. :P Wish I could post pics but I'm away from own computer now.
Have fun playing! You really can't go wrong with vines and flowers - try some unnatural psychedelic combinations and see how it looks!