Hi,
currently i am setting up an Ivy Set for realistic nature rendering. Until now i got this far (Quick viewport render):
What Do you think? Comments and critiques are very welcome!
This looks good so far man 
The shaping of the leaves looks really good
I would recommend researching the way ivy grows up different surfaces like trees and also thinner objects to get a better idea of how to model the ivy distribution. It twines a lot to look for support for its roots (On thinner surfaces, wouldn’t apply to the ivy on a tree like you have posted) in a timelapse you can see it rotating round and round looking for solid surfaces.
Heres some video resources for you -
Ivy Tree Timelapse - https://www.youtube.com/watch?v=HZBFxkiFirw
9 day vine timelapse - https://www.youtube.com/watch?v=R39lt03ptMI
Vine twining motion - https://www.youtube.com/watch?v=dTljaIVseTc
I would recommend putting a bit more time into your shaders. Real ivy has more reflection than this, and also has a more saturated color (In most cases anyway)
After looking at the ivy that grows in my garden, the roughness of the reflections tend to vary from leaf to leaf, some seem to be very rough, while others not at all.
Also, note that a lot of ivy leaves will have damage/decay on them along with eaten parts where bugs have got to them
I have attached a collection of images i have found to show you how the reflections act in different lighting environments.
It also shows what i mentioned about the saturation, and also the decay.
Hi, this is the latest update of the ivy leafs:
I added a little of gloss and translucency, therefore the color of the leafs now responds better to the light and gives a more natural result. i also added some small leafs, and i updated the shader of the main tendril. i also changed the size ration between leafs and tendril. i also added some of those tiny “claws” the ivy uses to hold tight on a wall.
The leaf distribution itself might need some tweaking, but is you look at ivy in nature, you can find many many types of leaf distribution.
Until here i am quite happy with the result and will put it to the “finished Projects” Section. Now that the ivy works well, i will take it as an asset into a lager nature scene.
What Do you think?
Wow, new update looks much, much better!
Nice work man, the subtle gloss, color change and decay really adds to the realism 
The claw roots are a really nice touch too.
Great work man, i like it 
Hi, this is a better Version. I did not notice that there was something wrong with the color saturation. This is now the final state:
Thanks for help and watching!
My preference is the first one actually.