Start out with the tools shown. Of course you'll need a little gumpaste too, mine is already colored red and yellow. The actual petal dust colors are not important, just a yellow and a red, the bottle is confectioner's glaze 50/50 mix.
With a 28g paper covered wire, I use brown tape (cut in 1/3's) to wrap around the top of a wire a few times, fold into a hook, and tape around a few more times (to make a sort of bud), then continue to tape down the wire.
Roll the yellow paste into a ball, there is a ruler to help with the sizes, but vary your sizes to be more natural. Make both red and yellow balls, with the red being slightly smaller.
Put a little water onto the tape bud and insert into one of the balls.
Attach at the base by pinching a little with your fingers.
Use a knife tool or tooth pick to create 3 veins in the red berries only, evenly spaced.
Dust the red berry with a little of the red petal dust and dip into the confectioner's glaze. Do the same with the yellow dust and yellow berry. I sometimes put a little brown dot on the end of the yellow ball. Set aside in styrofoam to dry a little.
Roll out some yellow gumpaste and cut with the small 3 petal cutter.
Place the petal onto a thick foam and use a ball or dogbone tool to curl each petal and soften it. Start from the tip of the petal and move toward the center as you press down a little and the petal should curl a little.
Place a little bit of water in the center of the petal and insert it onto the wire with the red berry.
Dust the back of the yellow petal with some yellow dust.
This is a finished bittersweet berry.
Using the brown tape (cut into 1/4 or 1/3) attach a couple of the berries together.
Keep taping the berries together, in small bunches of 3 or 4 and sometimes adding a yellow berry.
Whew! Here is the finished spray. I like to bend the brown wires like they are small twiggs to they aren't straight.