I posted a photo of a fir tree a couple of days ago. There are lots of videos out there using various techniques. Some more realistic than others, so it depends on the "look" you are looking for. I used a method by Martin Tarnrot for making black spruce I think is reasonably easy to do and yet has really good results. I took a piece of cedar board trimmed it to a 3/4 x 3/4 stock, cut it to length, whittled it into a tapered tree shape. scraped the trunk with a saw blade to get grooves (cedar is soft and easily cuts). drilled holes for wire branches, colored trunk, inserted wire branches, coated entire assembly with white glue, when dry coated again with white glue and sprinkled with 12 mm static grass, when dry sprayed with 3M adhesive and sprinkled with 6 mm static grass. Use your breath or a hair dryer to orient the fibers in a down position for both of the grasses. At this point you could leave it as is, add more 6mm grass or as I did sprayed with adhesive again and sprinkled ground cover over the branches to give some bulk. Aside from the drying time, these can be made pretty quickly. I had static grass and ground cover the color I wanted so I did not spray paint as Martin shows. As always a bit of color variation helps. This one is 13 inches tall and about 6 inches at the base. I did not use a static grass applicator, just tossed bits of grass at the branches to get them to stick to the glue. The top is just bits of grass bundles hand applied to tacky glue painted at the top. I was able to gently blow the fibers into the down position. This is more important with the long fibers to get the general shape. I have read hairspray over time will deteriorate and lose its hold so you will be back to the wildfire look.
This tree is really similar to Sidehack's using a dowel and wire, but the difference is with the ground foam versus static grass. BTW - if you get really adventurous try making Martin's oak tree he does in another video - wow.