This is a recent personal creation.I created Japanese lanterns.We are currently working on a project to remake maps created in the past.https://www.artstation.com/artwork/obDOyw
The first thing I did was to plan my environment and create the blockout. As I am using nanites I am not so much worrying about polycount. Of course, there are no crazy amounts of tris, but for some parts like the Jesus statue I just decimated it from and created auto UVs and then created textures.
Could create a few separate branch modules which can then be used multiple times to detail the tree. To create unique shapes, deformers could be used and/or a tiling segment repeated along splines.
I still create a plane and make models from that. For almost all my modeling needs. Just search for lowpoly modelling and you'll find plenty of attempts on how to create geometry. Pick your favorite