What are some different ways to style long hair on a guy?
With hair of that length, you should try braiding it. The simplest is a three strand plait from the nape. A bit more elaborate, probably needing your gf’s help to start with, would be a French Braid (lots of thin strands could make it almost invisible) lifted away from your nape. That would form a pocket where your tail could be coiled and tucked out of sight. Of course you could coil your braid into a chignon, but that might look too elaborate for your comfort level initially. Then there’s the Colonial look. Draw your hair straight back, clean and not too tight, catching and folding it at your nape into a “club” caught with a simple ribbon. High toned gentlemen used a “bag,” a simple cloth folded and tied to catch their hair at the nape. I would forego the powder, however, unless you were invited to a dress up shindig. Even then, I would favor “au natural” with two or three rows of horizontal curls at the ears.