A sponge brush is optional for this project, as some people tend to just use their fingers to apply. Personally, I like using a sponge brush over a paint brush, and I also use my fingers when necessary. To decoupage, dip your brush in the Mod Podge and paint a thin layer on a section of the jar. Once that layer becomes quite sticky (check by dabbing your finger on it), place a leaf on the jar. Paint more Mod Podge on top of the leaf in thin layers, making sure to smooth out the edges. It may take a few layers, but the leaf should stick to the jar. Don't be afraid to use your fingers to smooth out the leaf so that it is fully secure. Layer more leaves on top, filling the jar with as many as you desire. I didn't cover my jar fully, as I liked some of the negative space in between the leaves. Once all the leaves are on, it will take a few hours to dry completely. The tiny edges of the leaves may not stay completely down, but when the look is complete, you may barely even notice.
Finish off the top of the jar with rafia or ribbon to complete the look. Place a candle inside and watch it light the room with beautiful orange, red and green fall colors!