Doesn't look too bad, a pretty standard jacket... I'd say you'd need about five parts, and maybe some fimo/embroidery floss for the details.
You'd need the two front pieces (A) cut to fit around the front of the doll (with seam allowance) and a back piece (B) that will probably need a gusset to avoid odd folds (I made my first doll jacket sans gusset, and it looked weird.) You can make the sleeves wider at the bottom than at the top (c) and then cut separate strips for the overturned cuffs (or try turning up the sleeves, but they might wrinkle too much at a small scale. For the collar, I'd just cut a roughly-the-right-length white strip, pin it, then cut it to fit. All the small gold details could be embroidered/sewn on, and then just make the sash out of grey fabric and tie it 'round
If you've never made clothes before, I'd suggest buying a cheap jacket/t-shirt pattern for full sized people, and learning from that. While you're at the fabric store (fabricland for me, they usually have discount patterns cheap, if you aren't picky about what style you get) you could pick up some cheap fabric ends to experiment with, and work out the kinks in your pattern
I hope that helped some, I'm not much good at tutorials but that's pretty much how I make my plushie clothes- basic patterns, crude drawings, and lots of guess-and-check