The first Jade leaves are inserting straight in from the sides, almost at a slight upward angle so the leaves point down.
Insert all around the container.
Keep stripping off the very bottom leaves so there is stem to insert.
You can now see the obviously downward slant of the first leaves.
Other leaves will begin to angle upward, until you reach the center and the leaves can go straight up.
Angling down, straight out and then upward will mimic the look of a real plant.
Jade does a good job of filling in the basic framework of the overall arrangement.
Insert as many leaves as necessary to get a good base outline.
Remember, though, you have a lot of flowers to insert, so you don't have to pack the foam completely full.